[clang] [Clang] unrecognized html tag causing undesirable comment lexing (PR #152944)

[Oliver Hunt via cfe-commits]

https://github.com/ojhunt commented:

The html tag updates looks good to me - tags are correctly described.

There should be tests for each tag however. 

As @cor3ntin has reviewed previously, I'd like his sign off - but as a question to him: do we expect tests for invalid/unclosed tags? my default is to want such tests but that's entirely due to my former work :D

https://github.com/llvm/llvm-project/pull/152944