[Doc] rename component README file (#3662)

src/image/README.md

@@ -0,0 +1,87 @@
+# Image
+
+### Install
+
+``` javascript
+import { Image } from 'vant';
+
+Vue.use(Image);
+```
+
+## Usage
+
+### Basic Usage
+
+```html
+<van-image
+  width="100"
+  height="100"
+  src="https://img.yzcdn.cn/vant/cat.jpeg"
+/>
+```
+
+### Fit Mode
+
+```html
+<van-image
+  width="10rem"
+  height="10rem"
+  fit="contain"
+  src="https://img.yzcdn.cn/vant/cat.jpeg"
+/>
+```
+
+### Lazy Load
+
+```html
+<van-image
+  width="100"
+  height="100"
+  lazy-load
+  src="https://img.yzcdn.cn/vant/cat.jpeg"
+/>
+```
+
+```js
+import { Lazyload } from 'vant';
+
+Vue.use(Lazyload);
+```
+
+## API
+
+### Props
+
+| Attribute | Description | Type | Default |
+|------|------|------|------|
+| src | Src | `String` | - | - |
+| fit | Fit mode | `String` | `fill` | - |
+| alt | Alt | `String` | - | - |
+| width | Width | `String | Number` | - | - |
+| height | Height | `String | Number` | - | - |
+| lazy-load | Whether to enable lazy load，should register [Lazyload](#/en-US/lazyload) component | `Boolean` | `false` | - |
+
+### fit optional value
+
+| name | desctription |
+|------|------|
+| contain | Keep aspect ratio, fully display the long side of the image |
+| cover | Keep aspect ratio, fully display the short side of the image, cutting the long side |
+| fill | Stretch and resize image to fill the content box |
+| none | Not resize image |
+| scale-down | Take the smaller of `none` or `contain` |
+
+### Events
+
+| Event | Description | Arguments |
+|------|------|------|
+| click | Triggered when click image | event: Event |
+| load | Triggered when image loaded | - |
+| error | Triggered when image load failed | - |
+
+### Slots
+
+| Name | Description |
+|------|------|
+| loading | Custom loading placeholder |
+| error | Custom error placeholder |