add comment why in-place renaming does not work

src/main/java/org/jastadd/tooling/RelAstGrammarRefactoringSupportProvider.java

@@ -12,6 +12,8 @@ public class RelAstGrammarRefactoringSupportProvider extends RefactoringSupportP
 
   @Override
   public boolean isMemberInplaceRenameAvailable(@NotNull PsiElement elementToRename, @Nullable PsiElement context) {
+    // in-place rename is still not available since not all requirements are met
+    // see https://intellij-support.jetbrains.com/hc/en-us/community/posts/360006918740-How-do-I-enable-in-place-rename-Renaming-via-dialog-works-fine-
     return (elementToRename instanceof RelAstGrammarDeclaredName) || (elementToRename instanceof RelAstGrammarTypeReference);
   }