[llvm-branch-commits] [clang] 🍒[NFC][BoundsSafety] Give `counted_by_or_null`, `sized_by`, and `sized_by_or_null` their own documentation (#212877) (PR #217720)

[Dan Liew via llvm-branch-commits]

delcypher wrote:

@tru This is a cherry-pick of https://github.com/llvm/llvm-project/pull/212877. It had to be done manually because there's a merge conflict due to the recent RST -> markdown syntax switch for our documentation. This is just a documentation change so it should be harmless.

https://github.com/llvm/llvm-project/pull/217720