[Chapel Merge] document cache_get_hits etc

Branch: refs/heads/master
Revision: 4d90800
Author: mppf
Log Message:

Merge pull request #17433 from mppf/document-pr-16905

document cache_get_hits etc

Follow-up to PR #16905

Reviewed by @e-kayrakli - thanks!

Modified Files:
M modules/standard/CommDiagnostics.chpl

Compare: https://github.com/chapel-lang/chapel/compare/041d453ef099...4d908008f59d