[Doc] add click event document (#722)

docs/markdown/en-US/button.md

@@ -76,3 +76,9 @@ Use `tag` prop to custom button tag
 | loading | Whether show loading status | `Boolean` | `false` | - |
 | block | Whether to set display block | `Boolean` | `false` | - |
 | bottom-action | Whether to be action button | `Boolean` | `false` | - |
+
+### Event
+
+| Event | Description | Arguments |
+|-----------|-----------|-----------|
+| click | Triggered when click button and not disabled or loading | - |

docs/markdown/en-US/cell.md

@@ -82,7 +82,13 @@ Vue.use(Cell).use(CellGroup);
 | is-link | Whether to show link icon | `Boolean` | `false` | - |
 | required | Whether to show required mark | `Boolean` | `false` | - |
 
-### Slot
+### Cell Event
+
+| Event | Description | Arguments |
+|-----------|-----------|-----------|
+| click | Triggered when click cell | - |
+
+### Cell Slot
 
 | name | Description |
 |-----------|-----------|

docs/markdown/en-US/icon.md

@@ -29,3 +29,9 @@ import 'vant/lib/vant-css/icon-local.css';
 |-----------|-----------|-----------|-------------|-------------|
 | name | Icon name | `String` | `''` | - |
 | info | Info message | `String` | `''` | - |
+
+### Event
+
+| Event | Description | Arguments |
+|-----------|-----------|-----------|
+| click | Triggered when click icon | - |