[Tabs] Update onChange docs to match types (#15672)

* [Tab]s Update onChange signature to match docs

Changed the value from any to number to match the documentation at https://material-ui.com/api/tabs/

* Sebastian review

packages/material-ui/src/Tabs/Tabs.js

@@ -459,7 +459,7 @@ Tabs.propTypes = {
    * Callback fired when the value changes.
    *
    * @param {object} event The event source of the callback
-   * @param {number} value We default to the index of the child
+   * @param {any} value We default to the index of the child (number)
    */
   onChange: PropTypes.func,
   /**

pages/api/tabs.md

@@ -25,7 +25,7 @@ import Tabs from '@material-ui/core/Tabs';
 | <span class="prop-name">component</span> | <span class="prop-type">elementType</span> | <span class="prop-default">'div'</span> | The component used for the root node. Either a string to use a DOM element or a component. |
 | ~~<span class="prop-name">fullWidth</span>~~ | <span class="prop-type">bool</span> |  | *Deprecated*. Instead, use the `variant="fullWidth"` property.<br><br>If `true`, the tabs will grow to use all the available space. This property is intended for small views, like on mobile. |
 | <span class="prop-name">indicatorColor</span> | <span class="prop-type">enum:&nbsp;'secondary'&nbsp;&#124;<br>&nbsp;'primary'<br></span> | <span class="prop-default">'secondary'</span> | Determines the color of the indicator. |
-| <span class="prop-name">onChange</span> | <span class="prop-type">func</span> |  | Callback fired when the value changes.<br><br>**Signature:**<br>`function(event: object, value: number) => void`<br>*event:* The event source of the callback<br>*value:* We default to the index of the child |
+| <span class="prop-name">onChange</span> | <span class="prop-type">func</span> |  | Callback fired when the value changes.<br><br>**Signature:**<br>`function(event: object, value: any) => void`<br>*event:* The event source of the callback<br>*value:* We default to the index of the child (number) |
 | ~~<span class="prop-name">scrollable</span>~~ | <span class="prop-type">bool</span> |  | *Deprecated*. Instead, use the `variant="scrollable"` property.<br><br>If `true`, it will invoke scrolling properties and allow for horizontally scrolling (or swiping) of the tab bar. |
 | <span class="prop-name">ScrollButtonComponent</span> | <span class="prop-type">elementType</span> | <span class="prop-default">TabScrollButton</span> | The component used to render the scroll buttons. |
 | <span class="prop-name">scrollButtons</span> | <span class="prop-type">enum:&nbsp;'auto'&nbsp;&#124;<br>&nbsp;'on'&nbsp;&#124;<br>&nbsp;'off'<br></span> | <span class="prop-default">'auto'</span> | Determine behavior of scroll buttons when tabs are set to scroll `auto` will only present them on medium and larger viewports `on` will always present them `off` will never present them |