[cpp.predefined] Sub-links to feature macro version number constants overlayed with `⟵` arrow, making it unreadable

[whisperity]

For example when going from the index row of __cpp_modules to [cpp.predefined]#:__cpp_modules, there is an ⟵ arrow which is not clickable and leads nowhere, but is overlaying the first 3 characters of the macro value literal:

[Eelis]

Thanks for the report.