message: docs: should hide cell valueOnly demo in weapp
diff: <van-cell :title="$t('cell')" :value="$t('content')" icon="location-o" />
  </demo-block>
  - <demo-block :title="$t('valueOnly')">
  + <demo-block v-if="!$attrs.weapp" :title="$t('valueOnly')">
  <van-cell :value="$t('content')" />
  </demo-block>
  