Update mdn.js

Added note about Nodejs dependency.

Author: traynham

commands/web-searches/mdn.js

@@ -1,5 +1,8 @@
 #!/usr/bin/env node
 
+//	Dependency: This script requires Nodejs.
+// Install Node: https://nodejs.org/en/download/
+//
 // Required parameters:
 // @raycast.schemaVersion 1
 // @raycast.title MDN JS Docs