[boost] [website][string_ref] Broken link to the library docs

Hi, In the library list for Boost 1.84: https://www.boost.org/doc/libs/1_84_0/ there is an entry for Boost.StringRef. However, that library was removed from libs/utility/meta/libraries.json. Or, more precisely, it was renamed to Boost.StringView (key: utility/string_view). The problem is that the StringRef entry in the above list has a broken link to the library docs, and the rename was supposed to fix it (by having an entry for StringView instead, linking to its docs). I'm not sure where StringRef comes from, but can it be removed? This has been reported a few times already: https://github.com/boostorg/website/issues/763 https://github.com/boostorg/utility/issues/105