[clang-tools-extra] [clang-doc] Add standalone Markdown parsing library (PR #200302)

[Paul Kirth via cfe-commits]

https://github.com/ilovepi commented:

Some of the logging seems a bit excessive. we normally try to limit the debug logs to things we care about, and this seems a bit verbose/spammy. That doesn't mean its not useful, so if you found this level of logging helpful in tuning this set o patches, thats fine, but more typically I'd want more targeted logging, or logs that clearly delineate different operations. You may want to look at the logging in clang's parser, or some of the optimization passes to see what kinds of things people typically put into the debug output.

https://github.com/llvm/llvm-project/pull/200302