docs: fix todo comment

docusaurus/docs/React/guides/theming/message-ui.mdx

@@ -387,7 +387,7 @@ const CustomMessageUi = () => {
 
 Message grouping is being managed automatically by the SDK and each parent element (which holds our message UI) receives an appropriate class name based on which we can adjust our rules to display metadata elements only when it's appropriate to make our UI look less busy.
 
-{/_ TODO: link to grouping logic (maybe how to adjust it if needed) _/}
+[//]: # 'TODO: link to grouping logic (maybe how to adjust it if needed)'
 
 ```css
 .custom-message-ui__metadata {