Docs: Remove @staticvar tags from core.

The tag was supported in phpDocumentor 1.x, but is no longer supported in 2.x and 3.x.

Usage of static variables is considered an internal implementation detail and has no information value for someone reading the docs.

Props alishanvr, jrf.
Fixes #50426.

git-svn-id: https://develop.svn.wordpress.org/trunk@48109 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-rewrite.php

@@ -1786,8 +1786,6 @@ class WP_Rewrite {
 	 *
 	 * @since 2.0.1
 	 *
-	 * @staticvar bool $do_hard_later
-	 *
 	 * @param bool $hard Whether to update .htaccess (hard flush) or just update rewrite_rules option (soft flush). Default is true (hard).
 	 */
 	public function flush_rules( $hard = true ) {