Update README.md

This starter is no longer using the Beta of Gatsby V2. Replace detail and link in README.

Author: krisaoe

README.md

@@ -1,6 +1,6 @@
 # Gatsby + Netlify CMS Starter
 
-**Note:** This starter uses the [Gatsby v2 Beta](https://www.gatsbyjs.org/blog/2018-06-16-announcing-gatsby-v2-beta-launch/).
+**Note:** This starter uses [Gatsby v2](https://www.gatsbyjs.org/blog/2018-09-17-gatsby-v2/).
 
 This repo contains an example business website that is built with [Gatsby](https://www.gatsbyjs.org/), and [Netlify CMS](https://www.netlifycms.org): **[Demo Link](https://gatsby-netlify-cms.netlify.com/)**.