Update documentation label

Author: ojhunt

clang/include/clang/Basic/AttrDocs.td

@@ -8231,9 +8231,8 @@ its underlying representation to be a WebAssembly ``funcref``.
 
 def PreferredTypeDocumentation : Documentation {
   let Category = DocCatField;
+  let Label = "langext-preferred_type_documentation";
   let Content = [{
-.. _langext-preferred_type_documentation:
-
 This attribute allows adjusting the type of a bit-field in debug information.
 This can be helpful when a bit-field is intended to store an enumeration value,
 but has to be specified as having the enumeration's underlying type in order to