remove a doc(hidden) on read only version of derive(WorldQuery) (b…

…evyengine#6877)

having `doc(hidden)` on the read only version of a generated mutable world query leads to docs on the readonly item having a dead link. It also makes it annoying to have nice docs for libraries attempting to expose derived `WorldQuery` structs as re-exporting the read only item does not cause it to appear in docs even though it would be intended for users to know about the read only world query and use it.

crates/bevy_ecs/macros/src/fetch.rs

@@ -333,10 +333,9 @@ pub fn derive_world_query_impl(ast: DeriveInput) -> TokenStream {
     let readonly_impl = if fetch_struct_attributes.is_mutable {
         let world_query_impl = impl_fetch(true);
         quote! {
-            #[doc(hidden)]
-            #[doc = "Automatically generated internal [`WorldQuery`] type for [`"]
+            #[doc = "Automatically generated [`WorldQuery`] type for a read-only variant of [`"]
             #[doc = stringify!(#struct_name)]
-            #[doc = "`], used for read-only access."]
+            #[doc = "`]."]
             #[automatically_derived]
             #visibility struct #read_only_struct_name #user_impl_generics #user_where_clauses {
                 #( #field_idents: #read_only_field_types, )*