remove extra comma in components

Author: chrisvfritz

src/v2/guide/components.md

@@ -185,7 +185,7 @@ new Vue({
     posts: [
       { id: 1, title: 'My journey with Vue' },
       { id: 2, title: 'Blogging with Vue' },
-      { id: 3, title: 'Why Vue is so fun' },
+      { id: 3, title: 'Why Vue is so fun' }
     ]
   }
 })