doc: add CrOS install guide (#225)

* doc: add CrOS install guide
Signed-off-by: NHikari <enra@sayonika.moe>

* doc: change occurences of index to install guide
Signed-off-by: NHikari <enra@sayonika.moe>

* doc: add penguin.linux.test as alternative endpoint
Signed-off-by: NHikari <enra@sayonika.moe>

* doc: link Crostini and crouton info pages and describe install guide
Signed-off-by: NHikari <enra@sayonika.moe>

* doc: remove citations for dev mode requirement
Signed-off-by: NHikari <enra@sayonika.moe>

* doc: clarify more wording
Signed-off-by: NHikari <enra@sayonika.moe>

* doc: fix typo in Crostini section
Signed-off-by: NHikari <enra@sayonika.moe>

doc/self-hosted/cros-install.md

+# Installng code-server in your ChromiumOS/ChromeOS/CloudReady machine
+
+This guide will show you how to install code-server into your CrOS machine.
+
+## Using Crostini
+
+One of the easier ways to run code-server is via [Crostini](https://www.aboutchromebooks.com/tag/project-crostini/), the Linux apps support feature in CrOS. Make sure you have enough RAM, HDD space and your CPU has VT-x/ AMD-V support. If your chromebook has this, then you are qualified to use Crostini.
+
+If you are running R69, you might want to enable this on [Chrome Flags](chrome://flags/#enable-experimental-crostini-ui). If you run R72, however, this is already enabled for you.
+
+After checking your prerequisites, follow the steps in [the self-host install guide](index.md) on installing code-server. Once done, make sure code-server works by running it. After running it, simply go to `penguin.linux.test:8443` to access code-server. Now you should be greeted with this screen. If you did, congratulations, you have installed code-server in your Chromebook!
+
+![code-server on Chromebook](../assets/cros.png)
+
+Alternatively, if you ran code-server in another container and you need the IP for that specific container, simply go to Termina's shell via `crosh` and type `vsh termina`.
+
+```bash
+Loading extra module: /usr/share/crosh/dev.d/50-crosh.sh
+Welcome to crosh, the Chrome OS developer shell.
+
+If you got here by mistake, don't panic!  Just close this tab and carry on.
+
+Type 'help' for a list of commands.
+
+If you want to customize the look/behavior, you can use the options page.
+Load it by using the Ctrl+Shift+P keyboard shortcut.
+
+crosh> vsh termina
+(termina) chronos@localhost ~ $
+```
+While in termina, run `lxc list`. It should output the list of running containers.
+
+```bash
+(termina) chronos@localhost ~ $ lxc list
++---------+---------+-----------------------+------+------------+-----------+
+|  NAME   |  STATE  |         IPV4          | IPV6 |    TYPE    | SNAPSHOTS |
++---------+---------+-----------------------+------+------------+-----------+
+| penguin | RUNNING | 100.115.92.199 (eth0) |      | PERSISTENT | 0         |
++---------+---------+-----------------------+------+------------+-----------+
+(termina) chronos@localhost ~ $ 
+```
+
+For this example, we show the default `penguin` container, which is exposed on `eth0` at 100.115.92.199. Simply enter the IP of the container where the code-server runs to Chrome.
+
+## Using Crouton
+
+[Crouton](https://github.com/dnschneid/crouton) is one of the old ways to get a running full Linux via `chroot` on a Chromebook. To use crouton, enable developer mode and go to `crosh`. This time, run `shell`, which should drop you to `bash`.
+
+Make sure you downloaded `crouton`, if so, go ahead and run it under `~/Downloads`. After installing your chroot container via crouton, go ahead and enter `enter-chroot` to enter your container.
+
+Follow the instructions set in [the self-host install guide](index.md) to install code-server. After that is done, run `code-server` and verify it works by going to `localhost:8443`.
+
+> At this point in writing, `localhost` seems to work in this method. However, the author is not sure if it applies still to newer Chromebooks.