[Doc] rename component README file (#3662)

src/circle/README.md

@@ -0,0 +1,76 @@
+# Circle
+
+### Install
+``` javascript
+import { Circle } from 'vant';
+
+Vue.use(Circle);
+```
+
+## Usage
+
+### Basic Usage
+
+```html
+<van-circle
+  v-model="currentRate"
+  :rate="30"
+  :speed="100"
+  :text="text"
+/>
+```
+
+``` javascript
+export default {
+  data() {
+    return {
+      currentRate: 0
+    };
+  },
+  computed: {
+    text() {
+      return this.currentRate.toFixed(0) + '%'
+    }
+  }
+};
+```
+
+### Custom style
+
+```html
+<van-circle
+  v-model="currentRate"
+  color="#07c160"
+  fill="#fff"
+  size="120px"
+  layer-color="#ebedf0"
+  :text="text"
+  :rate="rate"
+  :speed="100"
+  :clockwise="false"
+  :stroke-width="60"
+/>
+```
+
+## API
+
+### Props
+
+| Attribute | Description | Type | Default |
+|------|------|------|------|
+| v-model | Current rate | `Number` | - |
+| rate | Target rate | `Number` | `100` |
+| size | Circle size | `String` | `100px` |
+| color | Progress bar color | `String` | `#1989fa` |
+| layer-color | Layer color | `String` | `#fff` |
+| fill | Fill color | `String` | `none` |
+| speed | Animate speed（rate/s）| `Number` | - |
+| text | Text | `String` | - |
+| stroke-width | Stroke width | `Number` | `40` |
+| clockwise | Is clockwise | `Boolean` | `true` |
+
+### Slots
+
+| Name | Description |
+|------|------|
+| default | custom text content |