clarify naming in counter event components example, fixes vuejs#1051

Author: chrisvfritz

src/v2/guide/components.md

@@ -501,14 +501,14 @@ Here's an example:
 
 ``` js
 Vue.component('button-counter', {
-  template: '<button v-on:click="increment">{{ counter }}</button>',
+  template: '<button v-on:click="incrementCounter">{{ counter }}</button>',
   data: function () {
     return {
       counter: 0
     }
   },
   methods: {
-    increment: function () {
+    incrementCounter: function () {
       this.counter += 1
       this.$emit('increment')
     }
@@ -536,14 +536,14 @@ new Vue({
 </div>
 <script>
 Vue.component('button-counter', {
-  template: '<button v-on:click="increment">{{ counter }}</button>',
+  template: '<button v-on:click="incrementCounter">{{ counter }}</button>',
   data: function () {
     return {
       counter: 0
     }
   },
   methods: {
-    increment: function () {
+    incrementCounter: function () {
       this.counter += 1
       this.$emit('increment')
     }