Audit Environment variables and update wiki

[Neil3079]

The wiki is out of date, across a few topics such as environment variables and lanes. Also worth a review of what environment variables we use

[KaneCheshire]

Issue #20: Audit Environment variables and update wiki

[Neil3079]

I think we can agree the wiki approach is not working, it isn't being updated and I'm pretty sure no one uses it. I propose we instead have some kind of ENVIRONMENT.md (better names welcomed) where we can list different environment variables and what they do.

Being part of this project will make it easier to update as we go along and should lead to more comprehensive and accessible documentation.

[KaneCheshire]

I've started a branch for this: https://github.com/theappbusiness/MasterFastfile/tree/chore/kc_readme