Snippet format update

To match the starter (for the migration)

snippets/isReadableStream.md

@@ -1,4 +1,7 @@
-### isReadableStream
+---
+title: isReadableStream
+tags: node,type,intermediate
+---
 
 Checks if the given argument is a readable stream.
 
@@ -17,4 +20,4 @@ const isReadableStream = val =>
 ```js
 const fs = require('fs');
 isReadableStream(fs.createReadStream('test.txt')); // true
-```
+```