Add Requires php to readme

Author: malmo-monei

readme.txt

@@ -4,6 +4,7 @@ Contributors: monei, furi3r
 Requires at least: 5.0
 Tested up to: 6.7
 Stable tag: 6.1.2
+Requires PHP: 7.2
 License: GPLv2 or later
 License URI: http://www.gnu.org/licenses/gpl-2.0.html
 WC requires at least: 3.0