docs: display all less variables (#7604)

src/switch/README.md

@@ -108,3 +108,21 @@ export default {
 | ------ | --------------------------------- | -------------- |
 | change | Emitted when check status changed | _value: any_   |
 | click  | Emitted when component is clicked | _event: Event_ |
+
+### Less Variables
+
+How to use: [Custom Theme](#/en-US/theme).
+
+| Name | Default Value | Description |
+| --- | --- | --- |
+| @switch-size | `30px` | - |
+| @switch-width | `2em` | - |
+| @switch-height | `1em` | - |
+| @switch-node-size | `1em` | - |
+| @switch-node-background-color | `@white` | - |
+| @switch-node-box-shadow | `0 3px 1px 0 rgba(0, 0, 0, 0.05)` | - |
+| @switch-background-color | `@white` | - |
+| @switch-on-background-color | `@blue` | - |
+| @switch-transition-duration | `@animation-duration-base` | - |
+| @switch-disabled-opacity | `@disabled-opacity` | - |
+| @switch-border | `@border-width-base solid rgba(0, 0, 0, 0.1)` | - |