Docs: Explicitly document the rest_revision_query filter.

The `rest_revision_query` filter in `WP_REST_Revisions_Controller::get_items()` carried a cross-reference comment claiming it was documented in the posts controller. This was incorrect, as the posts controller documents `rest_{$this->post_type}_query` — a dynamic hook that fires only for post types managed by `WP_REST_Posts_Controller`.

`WP_REST_Revisions_Controller` extends `WP_REST_Controller` directly (not the posts controller), so the dynamic hook never fires for revisions. `rest_revision_query` is a standalone hook and has never had its own PHPDoc block.

Follow-up to [43584].

Props apermo, mukesh27, SergeyBiryukov.
See #64224.

git-svn-id: https://develop.svn.wordpress.org/trunk@61998 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php

@@ -226,6 +226,8 @@ protected function get_revision( $id ) {
 	 *
 	 * @since 4.7.0
 	 *
+	 * @see WP_REST_Posts_Controller::get_items()
+	 *
 	 * @param WP_REST_Request $request Full details about the request.
 	 * @return WP_REST_Response|WP_Error Response object on success, or WP_Error object on failure.
 	 */
@@ -297,7 +299,17 @@ public function get_items( $request ) {
 				$args['update_post_meta_cache'] = false;
 			}
 
-			/** This filter is documented in wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php */
+			/**
+			 * Filters WP_Query arguments when querying revisions via the REST API.
+			 *
+			 * Serves the same purpose as the {@see 'rest_{$this->post_type}_query'} filter in
+			 * WP_REST_Posts_Controller, but for the standalone WP_REST_Revisions_Controller.
+			 *
+			 * @since 5.0.0
+			 *
+			 * @param array           $args    Array of arguments for WP_Query.
+			 * @param WP_REST_Request $request The REST API request.
+			 */
 			$args = apply_filters( 'rest_revision_query', $args, $request );
 			if ( ! is_array( $args ) ) {
 				$args = array();