rustdoc: Also run lint unused_doc_comments

Author: fmease

src/librustdoc/core.rs

@@ -230,6 +230,7 @@ pub(crate) fn create_config(
         // it's unclear whether these should be part of rustdoc directly (#77364)
         rustc_lint::builtin::MISSING_DOCS.name.to_string(),
         rustc_lint::builtin::INVALID_DOC_ATTRIBUTES.name.to_string(),
+	rustc_lint::builtin::UNUSED_DOC_COMMENTS.name.to_string(),
         // these are definitely not part of rustdoc, but we want to warn on them anyway.
         rustc_lint::builtin::RENAMED_AND_REMOVED_LINTS.name.to_string(),
         rustc_lint::builtin::UNKNOWN_LINTS.name.to_string(),