docs: update Button English doc (#7438)

Fixed some typos. Added ghost button type.

components/button/index.en-US.md

@@ -16,14 +16,14 @@ To get a customized button, just set `type`/`shape`/`size`/`loading`/`disabled`.
 
 Property | Description | Type | Default
 -----|-----|-----|------
-type | can be set to `primary` `dashed` `danger`(added in 2.7) or omitted | string | 'default'
-htmlType | to set the original `type` of `button`, see: [MDN](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button#attr-type) | string | `button`
+type | can be set to `primary` `ghost` `dashed` `danger`(added in 2.7) or omitted (meaning `default`) | string | `default`
+htmlType | set the original html `type` of `button`, see: [MDN](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button#attr-type) | string | `button`
 icon | set the icon of button, see: Icon component | string | -
 shape | can be set to `circle` or omitted | string | -
 size | can be set to `small` `large` or omitted | string | `default`
-loading | to set the loading status of button | boolean \| { delay: number } | `false`
+loading | set the loading status of button | boolean \| { delay: number } | false
 onClick | set the handler to handle `click` event | function | -
-ghost | make background transparent and invert text and border color, added in 2.7 | boolean | false
+ghost | make background transparent and invert text and border colors, added in 2.7 | boolean | false
 
 `<Button>Hello world!</Button>` will be rendered into `<button>Hello world!</button>`, and all the properties which are not listed above will be transferred to the `<button>` tag.