message: docs(Sticky): hide container demo in weapp
diff: <demo-section>
  <demo-block :title="$t('basicUsage')">
  <van-sticky>
  - <van-button
  - type="primary"
  - style="margin-left: 15px;"
  - >
  - {{ $t('basicUsage') }}
  - </van-button>
  + <van-button type="primary" style="margin-left: 15px;">{{ $t('basicUsage') }}</van-button>
  </van-sticky>
  </demo-block>
  <demo-block :title="$t('offsetTop')">
  <van-sticky :offset-top="50">
  - <van-button
  - type="info"
  - style="margin-left: 115px;"
  - >
  - {{ $t('offsetTop') }}
  - </van-button>
  + <van-button type="info" style="margin-left: 115px;">{{ $t('offsetTop') }}</van-button>
  </van-sticky>
  </demo-block>
  - <demo-block :title="$t('setContainer')">
  - <div
  - ref="container"
  - style="height: 150px; background-color: #fff;"
  - >
  + <demo-block v-if="!$attrs.weapp" :title="$t('setContainer')">
  + <div ref="container" style="height: 150px; background-color: #fff;">
  <van-sticky :container="container">
  - <van-button
  - type="warning"
  - style="margin-left: 215px;"
  - >
  - {{ $t('setContainer') }}
  - </van-button>
  + <van-button type="warning" style="margin-left: 215px;">{{ $t('setContainer') }}</van-button>
  </van-sticky>
  </div>
  </demo-block>
  @@ -66,7 +48,7 @@ export default {
  </script>
  <style lang="less">
  -@import "../../style/var";
  +@import '../../style/var';
  .demo-sticky {
  height: 200vh;
  