Form-Item Slot 自定义label内容

https://www.cnblogs.com/xufeikko/p/9780448.html

<el-form-item>
  <span slot="label">体&nbsp;&nbsp;&nbsp;重：</span>
  <el-input v-model="formTwo.weight" placeholder="单位千克" name="weight" ></el-input>
</el-form-item>