Documentation-related threads need their own category

The Development > DocC category is starting to become the default catchall for anything vaguely symbolgraph or API reference-related:

these topics don’t have a lot to do with the DocC tool specifically, and it’s not clear where to draw the line. for example, i posted DocC-style API reference now available for NIOCore, _Concurrency, and Swift modules a while back, which ended up getting moved to ‘Community Showcase’.

it also seems inconsistent given that:

Can we get a category just for documentation generation + API reference -related discussions?