Update README.md

Author: allendav

README.md

@@ -3,6 +3,10 @@ Amazon Payments gateway for WooCommerce
 
 Amazon Pay is embedded directly into your existing web site, and all the buyer interactions with Amazon Pay and Login with Amazon take place in embedded widgets so that the buyer never leaves your site. Buyers can log in using their Amazon account, select a shipping address and payment method, and then confirm their order. Requires an Amazon Pay seller account and supports USA, UK, Germany, France, Italy, Spain, Luxembourg, the Netherlands, Sweden, Portugal, Hungary, Denmark, and Japan.
 
+## Developer Wiki
+
+- https://github.com/woocommerce/woocommerce-gateway-amazon-pay/wiki
+
 ## NPM Scripts
 
 WooCommerce Gateway Amazon Payments Advanced utilizes npm scripts for task management utilities.