总订单：详情，优惠券信息处理

src/views/order/orderMr/dialog/details.vue

@@ -76,7 +76,9 @@
             <div class="grid-content bg-purple item-class">下单时间: <span>{{ form.createTime || '' }}</span></div>
           </el-col>
           <el-col :span="12">
-            <div class="grid-content bg-purple item-class">优惠信息: <span>暂无</span></div>
+            <div class="grid-content bg-purple item-class">优惠信息: 
+              <span>{{ form.coupon ? form.coupon.couponName : "暂无" }}</span>
+            </div>
           </el-col>
           <el-col :span="12">
             <div class="grid-content bg-purple item-class">支付时间: <span>{{ form.payTime || '' }}</span></div>