docs(Field): add basic usage document

src/form/demo/index.vue

@@ -1,64 +1,18 @@
 <template>
   <demo-section>
-    <demo-block :title="$t('basicUsage')">
-      <van-form @submit="onSubmit">
-        <van-field
-          v-model="username"
-          name="username"
-          label="username"
-          :rules="[{ required: true, message: 'username is required' }]"
-          placeholder="username"
-        />
-        <van-field
-          v-model="password"
-          type="password"
-          name="password"
-          label="password"
-          :rules="[{ required: true, message: 'password is required' }]"
-          placeholder="password"
-        />
-        <van-field
-          name="agree"
-          label="agree"
-          :rules="[{ required: true, message: 'need agree' }]"
-        >
-          <van-checkbox v-model="agree" slot="input" shape="square" />
-        </van-field>
-        <van-button type="primary">submit</van-button>
-      </van-form>
-    </demo-block>
+    <basic-usage />
+    <field-type />
   </demo-section>
 </template>
 
 <script>
+import BasicUsage from './BasicUsage';
+import FieldType from './FieldType';
+
 export default {
-  i18n: {
-    'zh-CN': {},
-    'en-US': {},
-  },
-
-  data() {
-    return {
-      username: '',
-      password: '',
-      agree: true,
-    };
-  },
-
-  methods: {
-    onSubmit(values) {
-      console.log(values);
-    },
+  components: {
+    BasicUsage,
+    FieldType,
   },
 };
 </script>
-
-<style lang="less">
-@import '../../style/var';
-
-.demo-form {
-  .van-button {
-    margin: 15px 0 0 15px;
-  }
-}
-</style>