Update README.md

Update the changelog.

Author: lukecav

README.md

@@ -30,6 +30,9 @@ Run ```composer require lukecav/performance-improvements-for-woocommerce```
 
 ## Changelog
 
+**1.1.18**
+* Bump WooCommerce tested version.
+
 **1.1.17**
 * Disable the Payment Gateway Admin Suggestions.