Add doc and demo for AutoComplete[placeholder], close #4044

components/auto-complete/demo/basic.md

@@ -43,6 +43,7 @@ const Complete = React.createClass({
         style={{ width: 200 }}
         onSelect={onSelect}
         onChange={this.handleChange}
+        placeholder="input here"
       />
     );
   },

components/auto-complete/demo/options.md

@@ -42,6 +42,7 @@ const Complete = React.createClass({
       <AutoComplete
         style={{ width: 200 }}
         onChange={this.handleChange}
+        placeholder="input here"
       >
         {children}
       </AutoComplete>

components/auto-complete/index.en-US.md

@@ -28,3 +28,4 @@ Since `AutoComplete` is based on `Select`, so besides the following API, `AutoCo
 | onChange | Called when select an option or input value change, or value of input is changed | function(value, label) | - |
 | onSelect | Called when a option is selected. param is option's value and option instance. | function(value, option) | -   |
 | disabled | Whether disabled select | boolean | false |
+| placeholder | placeholder of input | string | - |

components/auto-complete/index.zh-CN.md

@@ -29,3 +29,4 @@ const dataSource = ['12345', '23456', '34567'];
 | onChange | 选中 option，或 input 的 value 变化时，调用此函数 | function(value) | 无 |
 | onSelect | 被选中时调用，参数为选中项的 value 值	| function(value, option)	| 无 |
 | disabled | 是否禁用 | boolean | false |
+| placeholder | 输入框提示 | string | - |