Update form.md

examples/docs/en-US/form.md

@@ -399,7 +399,7 @@ Depending on your design, there are several different ways to align your label e
 
 Form component allows you to verify your data, helping you find and correct errors.
 
-:::demo Just add the `rule` attribute for `Form` component, pass validation rules, and set `prop` attribute for `Form-Item` as a specific key that needs to be validated. See more information at [async-validator](https://github.com/yiminghe/async-validator).
+:::demo Just add the `rules` attribute for `Form` component, pass validation rules, and set `prop` attribute for `Form-Item` as a specific key that needs to be validated. See more information at [async-validator](https://github.com/yiminghe/async-validator).
 
 ```html
 <el-form :model="ruleForm" :rules="rules" ref="ruleForm" label-width="120px" class="demo-ruleForm">