docs: 增加地图组件注意事项

pages/component/map/map.uvue

@@ -8,6 +8,7 @@
       @markertap="onmarkertap" @callouttap="oncallouttap" @controltap="oncontroltap" @regionchange="onregionchange" @tap="maptap"
       @updated="onupdated" @poitap="onpoitap"></map>
     <scroll-view class="scrollview" scroll-y="true">
+      <view>注意：需要正确配置地图服务商的Key才能正常显示地图组件</view>
       <view class="uni-title">
         <text class="uni-title-text">属性示例</text>
       </View>