Add wiki for installation on code-server

Seems like can't edit wiki directly.

For Home.md

### Installing font

- [OS Install instructions](https://github.com/tonsky/FiraCode/wiki/Installing)

### Enabling ligatures

You need to explicitly enable ligatures support in following editors:

- [Atom](https://github.com/tonsky/FiraCode/wiki/Atom-instructions)
- [BBEdit](https://github.com/tonsky/FiraCode/wiki/BBEdit-instructions)
- [Brackets](https://github.com/tonsky/FiraCode/wiki/Brackets-Instructions/)
- [ChromeOS Terminal](https://github.com/tonsky/FiraCode/wiki/ChromeOS-Terminal)
- [Cloud9](https://github.com/tonsky/FiraCode/wiki/cloud9-instructions)
- [Code Server - (VS Code for Web)](https://github.com/tonsky/FiraCode/wiki/code-server-instructions)
- [Emacs](https://github.com/tonsky/FiraCode/wiki/Emacs-instructions)
- [JetBrains' products](https://github.com/tonsky/FiraCode/wiki/Intellij-products-instructions) (IntelliJ, etc)
- [LaTeX](https://github.com/tonsky/FiraCode/wiki/LaTeX-instructions)
- [LightTable](https://github.com/tonsky/FiraCode/wiki/LightTable-instructions)
- [MacVim](https://github.com/tonsky/FiraCode/wiki/MacVim-instructions)
- [MATLAB Install instructions](https://github.com/tonsky/FiraCode/wiki/MATLAB-for-Windows-Instructions)
- [Notepad++](https://github.com/tonsky/FiraCode/wiki/Notepad-Plus-Plus-instructions)
- [Sublime Text](https://github.com/tonsky/FiraCode/wiki/Sublime-Text-Instructions)
- [VS Code](https://github.com/tonsky/FiraCode/wiki/VS-Code-Instructions)
- [Windows Terminal & Windows Terminal Preview](https://github.com/tonsky/FiraCode/wiki/Windows-Terminal-&-Windows-Terminal-Preview)

For other editors it should be enough to simply select Fira Code as your font of choice. [Full list of compatible editors](https://github.com/tonsky/FiraCode#editor-compatibility-list)

New wiki page: Code-Server-Instructions.md

## Requirements

Make sure you [install the font](https://github.com/tonsky/FiraCode/wiki/Linux-instructions).

Install [Stylus for Chrome](https://chromewebstore.google.com/detail/stylus/clngdbkpkpeebahjckkjfobafhncgmne) or [Stylus for Firefox](https://addons.mozilla.org/en-US/firefox/addon/styl-us/) and add this user style to the domain/URLs of code-server:

<code>@import url('https://fonts.googleapis.com/css2?family=Fira+Code:wght@300..700&display=swap');
</code>

## Using the visual Settings Editor

To open the settings editor: from the `Code` menu, choose `Preferences` > `Settings`, or use keyboard shortcut <kbd>Ctrl</kbd>+<kbd>,</kbd> (<kbd>Cmd</kbd>+<kbd>,</kbd> on Mac).

To enable FiraCode in the settings editor: under "Commonly Used", expand the "Text Editor" settings and then click on "Font". In the "Font Family" input box type `Fira Code`, replacing any content. Tick the check box "Enables/Disables font ligatures" under "Font Ligatures" to enable the special ligatures.

## Manually editing `settings.json`

Visual Studio Code allows you to also edit the underlying `settings.json` config file. First open the settings editor as described above, then click the "curly brackets" icon to open the `settings.json` file.

Then paste the following lines and save the file.

```json
"editor.fontFamily": "Fira Code",
"editor.fontLigatures": true,
```

If this doesn't work for you, you can try:

1. restarting VS Code;
1. wrapping the "Fira Code" section with additional apostrophes:
   ```json
   "editor.fontFamily": "'Fira Code'",
   "editor.fontLigatures": true,
   ```

### Font weights

To achieve different weights, add one of the following (verified on Mac/Windows 10):

```json
    "editor.fontWeight": "300" // Light
    "editor.fontWeight": "400" // Regular
    "editor.fontWeight": "500" // Medium
    "editor.fontWeight": "600" // Bold
    "editor.fontWeight": "700" // Extra Bold
```

### Stylistic sets

Since version [1.40](https://code.visualstudio.com/updates/v1_40#_font-feature-settings), you can define stylistic sets in `settings.json`:

```json
"editor.fontLigatures": "'calt', 'ss01', 'ss02', 'ss03', 'ss04', 'ss05', 'ss06', 'zero', 'onum'"
```

To avoid possible bugs, you must uninstall Fira Code 1.x before installing Fira Code 2+.

### Useful extensions

- [Disable ligatures in unwanted contexts](https://marketplace.visualstudio.com/items?itemName=kshetline.ligatures-limited) (be aware [of the issues](https://github.com/kshetline/ligatures-limited/issues))

Start with the issue body and the existing wiki Home.md structure. Add the Code Server entry there and create Code-Server-Instructions.md with the supplied installation, settings, ligature, weight, stylistic-set, and extension guidance. Done means both wiki pages contain the requested content and links render correctly.