[Documentation] Propagate backward added to the docs (#5434)

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- Propagate backward description added to the doc
- Related screenshots updated

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- [x] I submit my changes into the `develop` branch
- [ ] I have added a description of my changes into
[CHANGELOG](https://github.com/cvat-ai/cvat/blob/develop/CHANGELOG.md)
file
- [x] I have updated the [documentation](
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accordingly
- [ ] I have added tests to cover my changes
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[cvat-data](https://github.com/cvat-ai/cvat/tree/develop/cvat-data#versioning)
and
[cvat-ui](https://github.com/cvat-ai/cvat/tree/develop/cvat-ui#versioning))

### License

- [ ] I submit _my code changes_ under the same [MIT License](
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  Feel free to contact the maintainers if that's a concern.
Co-authored-by: NBoris Sekachev <boris.sekachev@yandex.ru>

site/content/en/docs/manual/basics/objects-sidebar.md

@@ -5,13 +5,14 @@ weight: 11
 description: 'Overview of available functions on the objects sidebar of the annotation tool.'
 ---
 
-## Hide objects sidebar
-
-`Hide` - the button hides the object's sidebar.
+In the objects sidebar, you can see the list of available objects on the current
+frame. The following figure is an example of how the list might look like:
 
-![](/images/image146.jpg)
+| Shape mode                | Track mode                |
+| ------------------------- | ------------------------- |
+| ![](/images/image044.jpg) | ![](/images/image045.jpg) |
 
-## Objects
+## Objects properties
 
 **Filter** input box
 
@@ -24,23 +25,16 @@ The way how to use filters is described in the advanced guide [here](/docs/manua
 ![](/images/image147.jpg)
 
 - Switch lock property for all - switches lock property of all objects in the frame.
-- Switch hidden property for all - switches hide property of all objects in the frame.
+- Switch hidden property for all - switches hide the property of all objects in the frame.
 - Expand/collapse all - collapses/expands the details field of all objects in the frame.
 - Sorting - sort the list of objects: updated time, ID - accent, ID - descent
 
-In the objects sidebar you can see the list of available objects on the current
-frame. The following figure is an example of how the list might look like:
-
-| Shape mode                | Track mode                |
-| ------------------------- | ------------------------- |
-| ![](/images/image044.jpg) | ![](/images/image045.jpg) |
-
 ---
 
-**Objects** on the side bar
+**Objects** on the sidebar
 
-The type of a shape can be changed by selecting **Label** property.
-For instance, it can look like shown on the figure below:
+The type of shape can be changed by selecting the **Label** property.
+For instance, it can look like shown in the figure below:
 
 ![](/images/image050.jpg)
 
@@ -52,28 +46,34 @@ The action menu calls up the button:
 
 The action menu contains:
 
-- `Create object URL` - puts a link to an object on the clipboard.
+- **Create object URL** - puts a link to an object on the clipboard.
   After you open the link, this object will be filtered.
-- `Make a copy`- copies an object. The keyboard shortcut is `Ctrl + C` `Ctrl + V`.
-- `Propagate` - Copies the form to several frames,
-  invokes a dialog box in which you can specify the number of copies
-  or the frame onto which you want to copy the object. The keyboard shortcut `Ctrl + B`.
+- **Make a copy** - copies an object. The keyboard shortcut is **Ctrl** + **C** > **Ctrl** + **V**.
+- **Propagate** function copies the form to multiple frames
+  and displays a dialog box where you can specify the number
+  of copies or the frame to which you want to copy the object.
+  The keyboard shortcut is **Ctr**l + **B**. <br>There are two options available:
+
+  - **Propagate forward** (![Fw propagate](/images/propagate_fw.png)) creates a
+    copy of the object on `N` _subsequent_ frames at the same position.
+  - **Propagate backward** (![Back propagate](/images/propagate_back.png)) creates
+    a copy of the object on `N` _previous_ frames at the same position.
 
   ![](/images/image053.jpg)
 
-- `To background` - moves the object to the background. The keyboard shortcut `-`,`_`.
-- `To foreground` - moves the object to the foreground. The keyboard shortcut `+`,`=`.
-- `Change instance color`- choosing a color using the color picker (available only in instance mode).
+- **To background** - moves the object to the background. The keyboard shortcut **-** or **\_**
+- **To foreground** - moves the object to the foreground. The keyboard shortcut **+** or **=**
+- **Change instance color**- choosing a color using the color picker (available only in instance mode).
 
   ![](/images/image153.jpg)
 
-- `Remove` - removes the object. The keyboard shortcut `Del`,`Shift+Del`.
+- **Remove** - removes the object. The keyboard shortcut **Del**, **Shift+Del**.
 
-A shape can be locked to prevent its modification or moving by an accident. Shortcut to lock an object: `L`.
+A shape can be locked to prevent its modification or moving by an accident. Shortcut to lock an object: **L**.
 
 ![](/images/image046.jpg)
 
-A shape can be **Occluded**. Shortcut: `Q`. Such shapes have dashed boundaries.
+A shape can be **Occluded**. Shortcut: **Q**. Such shapes have dashed boundaries.
 
 ![](/images/image048.jpg)
 
@@ -83,15 +83,15 @@ You can change the way an object is displayed on a frame (show or hide).
 
 ![](/images/image055.jpg)
 
-`Switch pinned property` - when enabled, a shape cannot be moved by dragging or dropping.
+**Switch pinned property** - when enabled, a shape cannot be moved by dragging or dropping.
 
 ![](/images/image052.jpg)
 
-`Tracker switcher` - enable/disable [tracking](/docs/manual/advanced/ai-tools#trackers) for the object.
+**Tracker switcher **- enable/disable [tracking](/docs/manual/advanced/ai-tools#trackers) for the object.
 
 ![](/images/tracker_switcher.jpg)
 
-By clicking on the `Details` button you can collapse or expand the field with all the attributes of the object.
+By clicking on the **Details** button you can collapse or expand the field with all the attributes of the object.
 
 ![](/images/image154.jpg)
 
@@ -99,7 +99,7 @@ By clicking on the `Details` button you can collapse or expand the field with al
 
 ## Labels
 
-In this tab you can lock or hide objects of a certain label.
+In this tab, you can lock or hide objects of a certain label.
 To change the color for a specific label,
 you need to go to the task page and select the color by clicking the edit button,
 this way you will change the label color for all jobs in the task.
@@ -108,18 +108,18 @@ this way you will change the label color for all jobs in the task.
 
 **Fast label change**
 
-You can change the label of an object using hot keys.
+You can change the label of an object using hotkeys.
 In order to do it, you need to assign a number (from 0 to 9) to labels.
 By default numbers 1,2...0 are assigned to the first ten labels.
 To assign a number, click on the button placed at the right of a label name on the sidebar.
 
 ![](/images/image210.jpg)
 
-After that you will be able to assign a corresponding label to an object
-by hovering your mouse cursor over it and pressing `Ctrl + Num(0..9)`.
+After that, you will be able to assign a corresponding label to an object
+by hovering your mouse cursor over it and pressing **Ctrl** + **Num(0..9)**.
 
-In case you do not point the cursor to the object, pressing `Ctrl + Num(0..9)` will set a chosen label as default,
-so that the next object you create (use `N` key) will automatically have this label assigned.
+In case you do not point the cursor to the object, pressing **Ctrl** + **Num(0..9)** will set a chosen label as default,
+so that the next object you create (use the `N` key) will automatically have this label assigned.
 
 ![](/images/image211.jpg)
 
@@ -129,9 +129,9 @@ so that the next object you create (use `N` key) will automatically have this la
 
 **Color By** options
 
-Change the color scheme of annotation:
+Change the color scheme of the annotation:
 
-- `Instance` — every shape has random color
+- `Instance` — every shape has a random color
 
   ![](/images/image095_detrac.jpg)
 
@@ -154,14 +154,15 @@ Change the opacity of every shape in the annotation.
 
 **Selected Fill Opacity** slider
 
-Change the opacity of the selected object's fill. It is possible to change opacity while drawing an object in the case
-of rectangles, polygons and cuboids.
+Change the opacity of the selected object's fill. It is possible
+to change the opacity while drawing an object in the case
+of rectangles, polygons, and cuboids.
 
 ![](/images/image089_detrac.jpg)
 
 **Outlines borders** checkbox
 
-You can change a special shape border color by clicking on the `Eyedropper` icon.
+You can change a special shape border color by clicking on the **Eyedropper** icon.
 
 ![](/images/image088_detrac.jpg)
 
@@ -173,6 +174,12 @@ If enabled all shapes are displayed in white and the background is black.
 
 **Show projections** checkbox
 
-Enables / disables the display of auxiliary perspective lines. Only relevant for cuboids
+Enables/disables the display of auxiliary perspective lines. Only relevant for cuboids
 
 ![](/images/image090_detrac.jpg)
+
+## Hide objects sidebar
+
+**Hide** - the button hides the object's sidebar.
+
+![](/images/image146.jpg)