[bugfix] Checkbox: should not render label when label is empty (#920)

docs/markdown/en-US/checkbox.md

@@ -12,7 +12,7 @@ Vue.use(Checkbox).use(CheckboxGroup);
 #### Basic Usage
 
 ```html
-<van-checkbox v-model="checked">Checkbox 1</van-checkbox>
+<van-checkbox v-model="checked">Checkbox</van-checkbox>
 ```
 
 ```javascript
@@ -28,7 +28,13 @@ export default {
 #### Disabled
 
 ```html
-<van-checkbox v-model="checked" disabled>Checkbox 2</van-checkbox>
+<van-checkbox v-model="checked" disabled>Checkbox</van-checkbox>
+```
+
+#### Disable Label click event
+
+```html
+<van-checkbox v-model="checked" label-disabled>Checkbox</van-checkbox>
 ```
 
 #### Checkbox Group
@@ -76,8 +82,8 @@ export default {
 ```html
 <van-checkbox-group v-model="result">
   <van-cell-group>
-    <van-cell v-for="(item, index) in list" :key="item">
-      <van-checkbox :name="item">Checkbox {{ item }}</van-checkbox>
+    <van-cell v-for="item in list" :title="`Checkbox ${item}`" :key="item">
+      <van-checkbox :name="item" />
     </van-cell>
   </van-cell-group>
 </van-checkbox-group>

docs/markdown/en-US/radio.md

@@ -44,8 +44,12 @@ export default {
 ```html
 <van-radio-group v-model="radio">
   <van-cell-group>
-    <van-cell><van-radio name="1">Radio 1</van-radio></van-cell>
-    <van-cell><van-radio name="2">Radio 2</van-radio></van-cell>
+    <van-cell :title="Radio 1" clickable @click="radio = '1'">
+      <van-radio name="1" />
+    </van-cell>
+    <van-cell :title="Radio 2" clickable @click="radio = '2'">
+      <van-radio name="2" />
+    </van-cell>
   </van-cell-group>
 </van-radio-group>
 ```