Core: Update docs related to running test

[ReverM]

What task needs to be completed?

https://github.com/ArchipelagoMW/Archipelago/blob/main/docs/running%20from%20source.md#running-tests and https://github.com/ArchipelagoMW/Archipelago/blob/main/docs/tests.md both have sections about running test.

• [ ] Add a link in the running from source doc to the test doc (possibly deleting the whole line)
• [ ] Add an example of what the archipelago directory is supposed to be. I had to do a bit of guess work in order to understand what it was
• [ ] Add information regarding the new button Berserker added

[black-sliver]

What new button?

I think we should retain the pytest, maybe just as "running tests without PyCharm". Also adding pytest-xdist in there wouldn't hurt: https://github.com/ArchipelagoMW/Archipelago/blob/main/.github/workflows/unittests.yml#L56 is what we do in CI to reduce runtime of tests. On my PC it speeds up tests ~7x and heats the room a lot faster.

[ReverM]

What new button?

[black-sliver]

Oh, unless I am mistaken that button isn't actually "new". It's just now hopefully always pre-configured to work.

[ReverM]

The doc should still mention it I think

[black-sliver]

Yeah, showing how to run tests is a good idea. I was just confused by the wording