Docs: Add Requires PHP header to readme.txt

See https://meta.trac.wordpress.org/ticket/2952#comment:13

Author: GaryJones

CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- `Requires PHP` header to `readme.txt`.
 
 ## [3.0.1] - 2017-08-24
 ### Fixed

readme.txt

@@ -4,7 +4,8 @@ Donate link: http://code.garyjones.co.uk/donate/
 Tags: genesis, js-no-js
 Requires at least: 4.6
 Tested up to: 4.8.1
-Stable tag: 2.1.0
+Requires PHP: 7.1
+Stable tag: 3.0.1
 
 Make front end styling easier for child themes on the Genesis Framework based on whether JavaScript is enabled or not.
 
@@ -71,5 +72,8 @@ See <a href="https://github.com/GaryJones/genesis-js-no-js/blob/master/CHANGELOG
 
 == Upgrade Notice ==
 
+= 3.0.1 =
+Requires PHP 7.1 and WordPress 4.6.
+
 = 3.0.0 =
 Requires PHP 7.1 and WordPress 4.6.