element中vpopover使用的小例子

应用自定义指令 v-popover 指向 Popover 的索引 ref 的例子：

`

    <el-form-item label="链接:" prop="dbUrl">
      <el-input
        v-model="dataSourceDetail.dbUrl"
        v-popover:popover1
        placeholder="请输出链接"
      >
      </el-input>
      <el-popover
        ref="popover1"
        placement="bottom"
        width="450"
        trigger="hover"
        :content="dbUrlTip"
      >
      </el-popover>
    </el-form-item>
    <el-form-item label="驱动类名:" v-popover:popover2 prop="driverClass">
      <el-input
        v-model="dataSourceDetail.driverClass"
        placeholder="请输出驱动类名"
      >
      </el-input>
      <el-popover
        ref="popover2"
        placement="bottom"
        width="450"
        trigger="hover"
        :content="driverClassTip"
      >
      </el-popover>

`