slot="tip"是不是就是指主体左上方的小角落
slot还有哪些值呢
我想

<el-upload v-if="isShowUpload" class="upload-demo" drag action="https://jsonplaceholder.typicode.com/posts/" accept=".xls,.xlsx" multiple>
   <i class="el-icon-upload"></i>
   <div class="el-upload__text">将文件拖到此处，或<em>点击上传</em></div>
   <div class="el-upload__tip" slot="tip">只能上传xls/xlsx文件</div>
</el-upload>

让el-upload__tip出现在·el-upload-dragger下方