Re-render details if rewrites are used (#34049)

* Add details about using rewrites

* Update docs/advanced-features/automatic-static-optimization.md

Co-authored-by: JJ Kasper <jj@jjsweb.site>

* link to isReady

Co-authored-by: JJ Kasper <jj@jjsweb.site>

docs/advanced-features/automatic-static-optimization.md

@@ -20,6 +20,14 @@ If the above is not the case, Next.js will **statically optimize** your page aut
 
 During prerendering, the router's `query` object will be empty since we do not have `query` information to provide during this phase. After hydration, Next.js will trigger an update to your application to provide the route parameters in the `query` object.
 
+The cases where the query will be updated after hydration triggering another render are:
+
+- The page is a [dynamic-route](/docs/routing/dynamic-routes.md).
+- The page has query values in the URL.
+- [Rewrites](/docs/api-reference/next.config.js/rewrites.md) are configured in your `next.config.js` since these can have parameters that may need to be parsed and provided in the `query`.
+
+To be able to distinguish if the query is fully updated and ready for use, you can leverage the `isReady` field on [`next/router`](/docs/api-reference/next/router.md#router-object).
+
 > **Note:** Parameters added with [dynamic routes](/docs/routing/dynamic-routes.md) to a page that's using [`getStaticProps`](/docs/basic-features/data-fetching/get-static-props.md) will always be available inside the `query` object.
 
 `next build` will emit `.html` files for statically optimized pages. For example, the result for the page `pages/about.js` would be:

docs/api-reference/next/router.md

@@ -50,7 +50,7 @@ The following is the definition of the `router` object returned by both [`useRou
 - `locales`: `String[]` - All supported locales (if enabled).
 - `defaultLocale`: `String` - The current default locale (if enabled).
 - `domainLocales`: `Array<{domain, defaultLocale, locales}>` - Any configured domain locales.
-- `isReady`: `boolean` - Whether the router fields are updated client-side and ready for use. Should only be used inside of `useEffect` methods and not for conditionally rendering on the server.
+- `isReady`: `boolean` - Whether the router fields are updated client-side and ready for use. Should only be used inside of `useEffect` methods and not for conditionally rendering on the server. See related docs for use case with [automatically statically optimized pages](/docs/advanced-features/automatic-static-optimization.md)
 - `isPreview`: `boolean` - Whether the application is currently in [preview mode](/docs/advanced-features/preview-mode.md).
 
 The following methods are included inside `router`: