Snippet format update

To match the starter (for the migration)

snippets/observeMutations.md

@@ -1,4 +1,7 @@
-### observeMutations
+---
+title: observeMutations
+tags: browser,event,advanced
+---
 
 Returns a new MutationObserver and runs the provided callback for each mutation on the specified element.
 
@@ -30,4 +33,4 @@ const observeMutations = (element, callback, options) => {
 ```js
 const obs = observeMutations(document, console.log); // Logs all mutations that happen on the page
 obs.disconnect(); // Disconnects the observer and stops logging mutations on the page
-```
+```