Docs: Corrections and improvements to types used in various docblocks.

See #51800, #52217


git-svn-id: https://develop.svn.wordpress.org/trunk@49936 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/post.php

@@ -813,7 +813,7 @@ function post_exists( $title, $content = '', $date = '', $type = '' ) {
  *
  * @global WP_User $current_user
  *
- * @return int|WP_Error
+ * @return int|WP_Error Post ID on success, WP_Error on failure.
  */
 function wp_write_post() {
 	if ( isset( $_POST['post_type'] ) ) {
@@ -889,7 +889,7 @@ function wp_write_post() {
  *
  * @since 2.0.0
  *
- * @return int|null
+ * @return int|void Post ID on success, void on failure.
  */
 function write_post() {
 	$result = wp_write_post();