[Meta] Reorganize guides around captured data types

Well, on that note, I think there's also a case to be made about reorganizing the JFR-related guides. The current layout and distribution of contents made sense when JFR was the only data type that Cryostat captured, but now that we also have thread and heap dumps, and async-profiler, there are probably better ways to organize all of this content.

But let's keep it all as-is for now and figure out a better organizational system and revamp it all later.

_Originally posted by @andrewazores in https://github.com/cryostatio/cryostatio.github.io/pull/259#discussion_r3211025328_