Form: Add label slot

examples/docs/en-US/form.md

@@ -765,3 +765,10 @@ Form component allows you to verify your data, helping you find and correct erro
 | rules | validation rules of form | object | — | — |
 | error | field error message, set its value and the field will validate error and show this message immediately | string | — | — |
 | show-message  | whether to show the error message | boolean | — | true |
+
+
+### Form-Item Slot
+| name | Description |
+|------|--------|
+| — | content of Form Item |
+| label | content of label |

examples/docs/zh-CN/form.md

@@ -753,3 +753,9 @@
 | rules    | 表单验证规则 | object | — | — |
 | error    | 表单域验证错误信息, 设置该值会使表单验证状态变为`error`，并显示该错误信息 | string | — | — |
 | show-message  | 是否显示校验错误信息 | boolean | — | true |
+
+### Form-Item Slot
+| name | 说明 |
+|------|--------|
+| — | Form Item 的内容 |
+| label | 标签文本的内容 |

packages/form/src/form-item.vue

@@ -5,7 +5,7 @@
     'is-required': isRequired || required
   }">
     <label :for="prop" class="el-form-item__label" v-bind:style="labelStyle" v-if="label">
-      {{label + form.labelSuffix}}
+      <slot name="label">{{label + form.labelSuffix}}</slot>
     </label>
     <div class="el-form-item__content" v-bind:style="contentStyle">
       <slot></slot>