feat: add ConfigProvider component (#8854)

src/config-provider/README.md

@@ -0,0 +1,82 @@
+# ConfigProvider
+
+### Intro
+
+Used to config the theme of Vant components.
+
+### Install
+
+Register component globally via `app.use`, refer to [Component Registration](#/en-US/advanced-usage#zu-jian-zhu-ce) for more registration ways.
+
+```js
+import { createApp } from 'vue';
+import { ConfigProvider } from 'vant';
+
+const app = createApp();
+app.use(ConfigProvider);
+```
+
+## Usage
+
+### Custom Theme
+
+Use `theme-vars` prop to custom theme variables。
+
+```html
+<van-config-provider :theme-vars="themeVars">
+  <van-form>
+    <van-field name="rate" label="Rate">
+      <template #input>
+        <van-rate v-model="rate" />
+      </template>
+    </van-field>
+    <van-field name="slider" label="Slider">
+      <template #input>
+        <van-slider v-model="slider" />
+      </template>
+    </van-field>
+    <div style="margin: 16px">
+      <van-button round block type="primary" native-type="submit">
+        Submit
+      </van-button>
+    </div>
+  </van-form>
+</van-config-provider>
+```
+
+```js
+import { ref } from 'vue';
+
+export default {
+  setup() {
+    const rate = ref(4);
+    const slider = ref(50);
+    const switchChecked = ref(true);
+
+    const themeVars = {
+      rateIconFullColor: '#07c160',
+      sliderBarHeight: '4px',
+      sliderButtonWidth: '20px',
+      sliderButtonHeight: '20px',
+      sliderActiveBackgroundColor: '#07c160',
+      buttonPrimaryBorderColor: '#07c160',
+      buttonPrimaryBackgroundColor: '#07c160',
+    };
+
+    return {
+      rate,
+      slider,
+      themeVars,
+      switchChecked,
+    };
+  },
+};
+```
+
+## API
+
+### Props
+
+| Attribute  | Description     | Type     | Default |
+| ---------- | --------------- | -------- | ------- |
+| theme-vars | Theme variables | _object_ | -       |