Add maintenance note

README.md

@@ -1,13 +1,18 @@
 ## Convert and E-Commerce app to a PWA
 
 E-Commerce demo app for the Progressive Web Applications instructor-led
-training. Based on Web Starter Kit (0.6.4)
+training. 
 
-## Getting Started
+__This is not an official Google product__
 
-To get started, check out the instructions on
-[developers.google.com](https://developers.google.com/web/ilt/pwa/challenge-convert-an-e-commerce-site-to-a-pwa).
+### In maintenance mode
+* This is based on Web Starter Kit (0.6.4) which is [no longer being 
+maintained](https://github.com/google/web-starter-kit/issues/940)
+* The code still runs, but note deprecation warnings from NPM.
+* This repository is in maintenance mode -- security issues are getting fixed, but new development would require taking it off the Web Starter Kit.
+* The PaymentRequest code [fails on Safari](https://github.com/google-developer-training/pwa-ecommerce-demo/issues/18). The linked issue supplements the lab notes and contains instructions for fixing it.
 
-## Note
+## Getting Started
 
-This is not an official Google product.
+To get started, check out the instructions on
+[developers.google.com](https://developers.google.com/web/ilt/pwa/challenge-convert-an-e-commerce-site-to-a-pwa).