Snippet format update

To match the starter (for the migration)

snippets/runPromisesInSeries.md

@@ -1,4 +1,7 @@
-### runPromisesInSeries
+---
+title: runPromisesInSeries
+tags: function,promise,intermediate
+---
 
 Runs an array of promises in series.
 
@@ -11,4 +14,4 @@ const runPromisesInSeries = ps => ps.reduce((p, next) => p.then(next), Promise.r
 ```js
 const delay = d => new Promise(r => setTimeout(r, d));
 runPromisesInSeries([() => delay(1000), () => delay(2000)]); // Executes each promise sequentially, taking a total of 3 seconds to complete
-```
+```