Documentation on simple-cgi-server.yaml

[BeardedTek]

It took me a little while to figure out how to bring environment variables into the server.

What do all the variables in simple-cgi-server.yaml do?

I'm currently using this project in a simple Docker container to run CGI Scripts to convert RTSP/RTMP/etc to MJPEG and JPG Snapshots:
https://github.com/beardedtek-com/rtsp2mjpg

Thanks for all the wonderful work on this! So much faster than the other options I've tried.