Docs: Add missing `@since` tag for [45031].

Props dimadin.
See #46667.

git-svn-id: https://develop.svn.wordpress.org/trunk@45191 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/link-template.php

@@ -2248,6 +2248,7 @@ function get_pagenum_link( $pagenum = 1, $escape = true ) {
 	 * Filters the page number link for the current request.
 	 *
 	 * @since 2.5.0
+	 * @since 5.2.0 Added the `$pagenum` argument.
 	 *
 	 * @param string $result  The page number link.
 	 * @param int    $pagenum The page number.