docs: AutoComplete document and demo improvement (ant-design#4840)

*  AutoComplete document and demo improvement

 + add a non-case-sensitive demo, close ant-design#4834.
 + remove confusing descriptions from document, close ant-design#4805.

* add snapshot

components/auto-complete/__tests__/__snapshots__/demo.test.js.snap

@@ -85,6 +85,50 @@ exports[`test renders ./components/auto-complete/demo/basic.md correctly 1`] = `
 </div>
 `;
 
+exports[`test renders ./components/auto-complete/demo/non-case-sensitive.md correctly 1`] = `
+<div
+  class="ant-select-show-search ant-select-auto-complete ant-select ant-select-combobox ant-select-enabled"
+  style="width:200px;">
+  <div
+    aria-autocomplete="list"
+    aria-expanded="false"
+    aria-haspopup="true"
+    class="ant-select-selection
+              ant-select-selection--single"
+    role="combobox">
+    <div
+      class="ant-select-selection__rendered">
+      <div
+        class="ant-select-selection__placeholder"
+        style="display:block;user-select:none;-webkit-user-select:none;"
+        unselectable="unselectable">
+        try to type \`b\`
+      </div>
+      <ul>
+        <li
+          class="ant-select-search ant-select-search--inline">
+          <div
+            class="ant-select-search__field__wrap">
+            <input
+              class="ant-input ant-input ant-select-search__field"
+              type="text"
+              value="" />
+            <span
+              class="ant-select-search__field__mirror" />
+          </div>
+        </li>
+      </ul>
+    </div>
+    <span
+      class="ant-select-arrow"
+      style="user-select:none;-webkit-user-select:none;"
+      unselectable="unselectable">
+      <b />
+    </span>
+  </div>
+</div>
+`;
+
 exports[`test renders ./components/auto-complete/demo/options.md correctly 1`] = `
 <div
   class="ant-select-show-search ant-select-auto-complete ant-select ant-select-combobox ant-select-enabled"

components/auto-complete/demo/non-case-sensitive.md

@@ -0,0 +1,31 @@
+---
+order: 3
+title:
+  zh-CN: 不区分大小写
+  en-US: Non-case-sensitive AutoComplete
+---
+
+## zh-CN
+
+不区分大小写的 AutoComplete
+
+## en-US
+
+A non-case-sensitive AutoComplete
+
+````jsx
+import { AutoComplete } from 'antd';
+
+const dataSource = ['Burns Bay Road', 'Downing Street', 'Wall Street'];
+
+function Complete() {
+  return (<AutoComplete
+    style={{ width: 200 }}
+    dataSource={dataSource}
+    placeholder="try to type `b`"
+    filterOption={(inputValue, option) => option.props.children.toUpperCase().indexOf(inputValue.toUpperCase()) !== -1}
+  />);
+}
+
+ReactDOM.render(<Complete />, mountNode);
+````

components/auto-complete/demo/uncertain-category.md

@@ -1,5 +1,5 @@
 ---
-order: 3
+order: 4
 title:
   zh-CN: 查询模式 - 不确定类目
   en-US: Lookup-Patterns - Uncertain Category

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

@@ -17,7 +17,6 @@ When there is a need for autocomplete functionality.
 const dataSource = ['12345', '23456', '34567'];
 <AutoComplete dataSource={dataSource} />
 ```
-Since `AutoComplete` is based on `Select`, so besides the following API, `AutoComplete` has the same API as `Select`.
 
 | Property           | Description                             |  Type | Default |
 |----------------|----------------------------------|------------|--------|
@@ -31,3 +30,4 @@ Since `AutoComplete` is based on `Select`, so besides the following API, `AutoCo
 | placeholder | placeholder of input | string | - |
 | children (for dataSource) | Data source for autocomplet | React.ReactElement<OptionProps> /  Array<React.ReactElement<OptionProps>> | - |
 | children (for customize input element) | customize input element | HTMLInputElement / HTMLTextAreaElement / React.ReactElement<InputProps> | `<Input />` |
+| 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     |

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

@@ -2,7 +2,7 @@
 category: Components
 subtitle: 自动完成
 type: Data Entry
-cols: 1
+cols: 2
 title: AutoComplete
 ---
 
@@ -18,7 +18,6 @@ title: AutoComplete
 const dataSource = ['12345', '23456', '34567'];
 <AutoComplete dataSource={dataSource} />
 ```
-因为 `AutoComplete` 是基于 `Select` 封装的，所以除了以下 API 外，`AutoComplete` 跟 `Select` 拥有一样的 API。
 
 | 参数           | 说明                             | 类型        | 默认值 |
 |----------------|----------------------------------|------------|---------|
@@ -33,3 +32,4 @@ const dataSource = ['12345', '23456', '34567'];
 | children (自动完成的数据源) | 自动完成的数据源 | React.ReactElement<OptionProps> / Array<React.ReactElement<OptionProps>> | - |
 | 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     |