[clang] [llvm] [clang-format] Add CI check confirming ClangFormatStyleOptions.rst is up-to-date. (PR #111513)

[Owen Pan via cfe-commits]

owenca wrote:

> > Because only part of the doc is generated by dump_format_style.py.
> 
> It should still be possible to only include the non-generated parts in the repo and then modify the script to add all the generated components on afterwards as a build step? Not sure if I'm missing something here.

Sometimes we need to edit the non-generated parts, and it would be easier to have the entire contexts. Anyway, don't we need the generated RST file in the repo so that the corresponding HTML file (e.g. https://clang.llvm.org/docs/ClangFormatStyleOptions.html) will be readily available?

https://github.com/llvm/llvm-project/pull/111513