Add Sublime Text setup documentation

[joshuadavidthomas]

First draft instructions:

1. Install the LSP client package for Sublime Text
2. Install Djaneiro package -- there may be another way, but as a non-Sublime user this seemed like the easiest way to get an htmldjango filetype
3. Add the following settings to the LSP settings

{
	"clients": {
    	"djls": {
    		"enabled": true,
      		"command": [
        		"djls",
        		"serve"
      		],
      		"selector": "text.html.django",
    	},
	},
}

Of course, this is pending #69 -- Sublime uses subprocess to launch the server, so it won't work currently.

[joshuadavidthomas]

Ah, you can pass environment variables to the underlying process: https://lsp.sublimetext.io/client_configuration/#:~:text=env,process%20(eg.%20PYTHONPATH)

[joshuadavidthomas]

Though that does nothing for me as a global setting.. 🤦‍♂️