[clang-tools-extra] [clang-doc] Add option for compact JSON (PR #190822)

[Paul Kirth via cfe-commits]

https://github.com/ilovepi approved this pull request.

LGTM. I left one small Q for you (totally up to you to change it or keep the current spelling), and something we should probably think about in our testing to make things simpler long-term.  IMO this is fine to land as is.

https://github.com/llvm/llvm-project/pull/190822