Write the example config, including every current config option for every module

We will need to keep this file up to date every time we add a config option or change a default.

I wrote this specifically because Ashton wanted to play around with the server but there was no docs on the config options.
It's fine to leave this as is as long as it's clear (possibly clearer than it is) that AutoJoin **must** be loaded for this to do anything and if the AutoJoin module is commented by default.