update en/application-dev/reference/apis/js-apis-eventhub.md.

Signed-off-by: Nking_he <6384784@qq.com>

en/application-dev/reference/apis/js-apis-eventhub.md

 # EventHub
 
-> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**
+> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**<br>
 > The initial APIs of this module are supported since API 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.
 
 
@@ -34,10 +34,10 @@ Subscribes to an event.
 
 **Parameters**
 
-  | Name| Type| Mandatory| Description| 
+  | Name| Type| Mandatory| Description | 
   | -------- | -------- | -------- | -------- |
-  | event | string | Yes| Event name.| 
-  | callback | Function | Yes| Callback invoked when the event is triggered.| 
+  | event | string | Yes| Event name. | 
+  | callback | Function | Yes| Callback invoked when the event is triggered. | 
 
 **Example**
     
@@ -74,8 +74,8 @@ Unsubscribes from an event. If **callback** is specified, this API unsubscribes
 
   | Name| Type| Mandatory| Description| 
   | -------- | -------- | -------- | -------- |
-  | event | string | Yes| Event name.| 
-  | callback | Function | No| Callback for the event. If **callback** is unspecified, all callbacks of the event are unsubscribed.| 
+  | event | string | Yes| Event name. | 
+  | callback | Function | No | Callback for the event. If **callback** is unspecified, all callbacks of the event are unsubscribed. | 
 
 **Example**
     
@@ -112,8 +112,8 @@ Triggers an event.
 
   | Name| Type| Mandatory| Description| 
   | -------- | -------- | -------- | -------- |
-  | event | string | Yes| Event name.| 
-  | ...args | Object[] | Yes| Variable parameters, which are passed to the callback when the event is triggered.| 
+  | event | string | Yes| Event name. | 
+  | ...args | Object[] | Yes| Variable parameters, which are passed to the callback when the event is triggered. | 
 
 **Example**