I wrote up a big effortpost about indirect conditions for nex on the [DS3 3.0 PR](https://github.com/ArchipelagoMW/Archipelago/pull/3128#discussion_r1693843193).
The version I'm [PRing to the world API document](https://github.com/ArchipelagoMW/Archipelago/pull/3552) is very brief and unnuanced, because I'd rather people use too many indirect conditions than too few.
But that might leave some devs wanting to know more.
I think that comment on nex's DS3 PR is probably the best detailed explanation for indirect conditions that exists currently.
So I think it's good if it exists somewhere. And the FAQ doc seems like the best place right now, because I don't want to write an entirely new doc at the moment.
* adding one faq :)
* adding another faq that links to the relevant file
* add lined line breaks between questions and lower the heading size of the question so sub-divisions can be added later
* missed some newlines
* updating best practice filler method
* add note about get_filler_item_name()
* updates to wording from review
* add section to CODEOWNERS for maintainers of this doc
* use underscores to reference the file easier in CODEOWNERS
* update link to be direct and filter to function name
