docs: Add backfill to AutoComplete

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

@@ -34,3 +34,4 @@ const dataSource = ['12345', '23456', '34567'];
 | children (for customize input element) | customize input element | HTMLInputElement / HTMLTextAreaElement / React.ReactElement<InputProps> | `<Input />` |
 | optionLabelProp | Which prop value of option will render as content of select. | string | `children` |
 | filterOption | If true, filter options by input, if function, filter options against it. The function will receive two arguments, `inputValue` and `option`, if the function returns `true`, the option will be included in the filtered set; Otherwise, it will be excluded. | boolean or function(inputValue, option) | true     |
+| backfill | backfill selected item the input when using keyboard  | bollean | false |

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

@@ -35,3 +35,4 @@ const dataSource = ['12345', '23456', '34567'];
 | children (自定义输入框) | 自定义输入框 |  HTMLInputElement / HTMLTextAreaElement / React.ReactElement<InputProps> | `<Input />` |
 | optionLabelProp | 回填到选择框的 Option 的属性值，默认是 Option 的子元素。比如在子元素需要高亮效果时，此值可以设为 `value`。 | string | `children` |
 | filterOption | 是否根据输入项进行筛选。当其为一个函数时，会接收 `inputValue` `option` 两个参数，当 `option` 符合筛选条件时，应返回 `true`，反之则返回 `false`。 | boolean or function(inputValue, option) | true     |
+| backfill | 使用键盘选择选项的时候把选中项回填到输入框中 | bollean | false |

package.json

@@ -60,7 +60,7 @@
     "rc-pagination": "~1.12.0",
     "rc-progress": "~2.2.2",
     "rc-rate": "~2.1.1",
-    "rc-select": "~6.8.6",
+    "rc-select": "~6.9.0",
     "rc-slider": "~8.2.0",
     "rc-steps": "~2.5.1",
     "rc-switch": "~1.5.1",