adding language tag as env var and document env vars

[pwnyprod]

No description provided.

[aPinat]

First of all, I never really wanted to add more info/instructions/documentation to this repo for many reasons.

Secondly, the pretty much all the changes you are making are either completely wrong or irrelevant:

• Changing hl is useless as it only changes the language the esports API is responding in and absolutely does not have to do with actual location or perhaps the leagues returned. However you then fail to see whether actual geolocation might matter further below in the code.
• Your descriptions for key and token are absolutely incorrect and you should have seen that, if you actually tried it out.