Minor fix (vuejs#329)

yanxyz · kazupon · commit c5847fa498e9 · 2016-06-29T12:46:05.000+09:00
diff --git a/src/api/index.md b/src/api/index.md
@@ -1161,7 +1161,7 @@ type: api
 
   // set a non-existent path, will force digest
   vm.$set('c', 3)
-  vm.c // ->
+  vm.c // -> 3
   ```
 
 - **See also:** [Reactivity in Depth](/guide/reactivity.html)
