Snippet format update

To match the starter (for the migration)

snippets/isStream.md

@@ -1,4 +1,7 @@
-### isStream
+---
+title: isStream
+tags: node,type,intermediate
+---
 
 Checks if the given argument is a stream.
 
@@ -11,4 +14,4 @@ const isStream = val => val !== null && typeof val === 'object' && typeof val.pi
 ```js
 const fs = require('fs');
 isStream(fs.createReadStream('test.txt')); // true
-```
+```