Improve turbolift documentation

[checkraisefold]

Description of issue

https://github.com/vlggms/tegustation-bay12/blob/dev/code/modules/turbolift/_turbolift.dm
this documentation sucks; namely it doesnt point out two things you have to codedive/check debug logs and runtimes for when it breaks after the fact.

1. each floor needs a different area type or it wont work with a runtime thrown
2. each area needs to be a subtype of /area/turbolift or it wont work with a debug log thrown
3. its kind of obvious but it should be more clear that you have to varedit in the map the areas_to_use and depth of the turbolift_map_holder for it to work