Add readme - example included

[joshring]

Note these were tested on Ubuntu, but should work on Mac too, windows will need to tweak the paths slightly

Install instructions

1.) Clone the C3 LSP repo: https://github.com/pherrymason/c3-lsp
2.) Build the C3 LSP with the instructions giving a binary at: c3_lsp_repo_path/server/bin/c3-lsp
3.) Set the following options in the vscode settings.json

"c3.lsp.enable": true,
"c3.lsp.path": "c3_lsp_repo_path/server/bin/c3-lsp"

4.) Clone this repo: https://github.com/c3lang/vscode-c3
5.) Starting this extension by opening extension.js and run by pressing F5
6.) A new window will appear, you can now open a C3 file or project folder

[lyubomyrk]

I followed the instruction and they work, however I never worked with js or vscode extensions so it took me some time to understand

5.1) Open vscode-c3 repo with code .
5.2) Open extension.js, press F5 and run with the vscode extension debugger

but I don't think it's ready for use

[lyranie]

implemented in #21