[clang] [NFC][clang] Quote literal builtin attribute markers in Builtins.def docs (PR #160080)

[Erich Keane via cfe-commits]

erichkeane wrote:

> > > and just left a 'link' to it here instead?
> > 
> > 
> > Also, is there a reason why we can’t just delete this file entirely and put the link e.g. in `Builtins.td`/`BuiltinsBase.td`
> 
> Since this isn't useful for the tablegen files I'm not sure that makes a ton of sense. Maybe rather put a comment in the `Builtins*.def` files that still exist?

I guess I was going for a little bit of a 'lower touch' ask :D  I don't mind that, but yes, it applies to .def files, so should be in the .def files.

There is a mild argument for "docs were ALWAYS here, so to not confuse folks, leave the file with just the doc link for a while", but I'm not sure how helpful/problematic that/this would be for folks that use this doc.

https://github.com/llvm/llvm-project/pull/160080