Add info for Linux/Proton installation

[powersupersport]

I see someone made a script for installing ToU on Linux: #198
https://gist.github.com/camarokris/d3081f167a8d40764b5a66695c953b94

There's also BepInEx's instructions:
https://docs.bepinex.dev/articles/advanced/proton_wine.html

It would be nice some instructions are provided in the readme (https://github.com/eDonnes124/Town-Of-Us-R/blob/master/README.md) on how to get this mod running on Linux. At bare minimum, maybe the links above can be added. It boils down to a single line of text that needs to be added to a file for this mod to work.

I can also make a draft in a pull request if you're interested.