Docs: Correct some version numbers.

`wp_check_for_changed_dates()`, `_find_post_by_old_slug(), `_find_post_by_old_date()`, and the `old_slug_redirect_post_id` filter were intended to land in 4.9.2, but didn't quite make it. Instead, they'll be landing in 4.9.3.

See #15397.



git-svn-id: https://develop.svn.wordpress.org/trunk@42588 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/post.php

@@ -5720,7 +5720,7 @@ function wp_check_for_changed_slugs( $post_id, $post, $post_before ) {
  * The most logically usage of this function is redirecting changed post objects, so
  * that those that linked to an changed post will be redirected to the new post.
  *
- * @since 4.9.2
+ * @since 4.9.3
  *
  * @param int     $post_id     Post ID.
  * @param WP_Post $post        The Post Object