docs(next/router): Update router.push api (vercel#24833)

Documentation page: https://nextjs.org/docs/api-reference/next/router#routerpush

Add `locale`  as supported options in `route.push()` (vercel#17898)

docs/api-reference/next/router.md

@@ -74,6 +74,7 @@ router.push(url, as, options)
 - `options` - Optional object with the following configuration options:
   - `scroll` - Optional boolean, controls scrolling to the top of the page after navigation. Defaults to `true`
   - [`shallow`](/docs/routing/shallow-routing.md): Update the path of the current page without rerunning [`getStaticProps`](/docs/basic-features/data-fetching.md#getstaticprops-static-generation), [`getServerSideProps`](/docs/basic-features/data-fetching.md#getserversideprops-server-side-rendering) or [`getInitialProps`](/docs/api-reference/data-fetching/getInitialProps.md). Defaults to `false`
+  - `locale` - Optional string, indicates locale of the new page
 
 > You don't need to use `router.push` for external URLs. [window.location](https://developer.mozilla.org/en-US/docs/Web/API/Window/location) is better suited for those cases.