Update README.md to include Session 9

README.md

@@ -25,4 +25,5 @@ Until the first full release, Blazor will always require the newest **preview**
 | [Session #6](/docs/06-authentication-and-authorization.md) | Authenticate users and authorize access to order status |
 | [Session #7](/docs/07-javascript-interop.md) | Track order status on a real time map |
 | [Session #8](/docs/08-templated-components.md) | Create and use components with template parameters |
+| [Session #9](/docs/09-progressive-web-app.md) | Progressive Web App (PWA) features |
 | [Session #10](/docs/10-publish-and-deploy.md) | Deploy your app to Azure |