Docs: Dev FAQ - About indirect conditions

I wrote up a big effortpost about indirect conditions for nex on the [DS3 3.0 PR](#3128 (comment)).

The version I'm [PRing to the world API document](#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.

docs/apworld_dev_faq.md

@@ -43,3 +43,11 @@ A faster alternative to the `for` loop would be to use a [list comprehension](ht
 ```py
 item_pool += [self.create_filler() for _ in range(total_locations - len(item_pool))]
 ```
+
+---
+
+### I learned about indirect conditions in the world API document, but I want to know more. What are they and why are they necessary?
+
+The world API document mentions indirect conditions and **when** you should use them, but not *how* they work and *why* they are necessary. This is because the explanation is quite complicated.
+
+It might get its own document in the future, but for now, you can read [this comment written by NewSoupVi](https://github.com/ArchipelagoMW/Archipelago/pull/3128#discussion_r1693843193) (and the other comments in that reply thread if you're still curious to learn more). As of the time of writing, it reflects the most up to date understanding of indirect conditions.