Docs: Document `$ini_all` staticvar in `wp_is_ini_value_changeable()`.

Props nileshdudakiya94.
Fixes #41399.

git-svn-id: https://develop.svn.wordpress.org/trunk@41922 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/load.php

@@ -1014,6 +1014,8 @@ function wp_convert_hr_to_bytes( $value ) {
  *
  * @since 4.6.0
  *
+ * @staticvar array $ini_all
+ *
  * @link https://secure.php.net/manual/en/function.ini-get-all.php
  *
  * @param string $setting The name of the ini setting to check.