b-errouane

Document configuration via environment variables in the wiki

3

Librespot implements the usage of environment variables instead of CLI parameters for configuration. I only found out because I did go through [the code](https://github.com/librespot-org/librespot/blob/131310b920bda545a5cb28789e96d1f83524212f/src/main.rs#L603). It would have been nice to...