增加指向图例

src/views/risk/drawCanvas/index.vue

 <template>
   <div class="wrap" ref="mapmidbox">
-    <!-- <div class="north">
-      <img src="../../assets/imgs/north.png" alt="" />
-    </div> -->
+    <div class="north">
+      <img src="../../assets/images/north.png" alt="" />
+    </div>
     <grid-layout
       id="gridView"
       :layout.sync="layout"