Add new Tools-section and mention Gatsby-Docker

As suggested here: https://twitter.com/gatsbyjs/status/964531323606986752

Author: aripalo

docs/docs/awesome-gatsby.md

@@ -16,6 +16,10 @@ See the [list of official and community starters](/docs/gatsby-starters/)
 
 See the [list of official and community plugins](/docs/plugins/)
 
+## Tools
+
+* [Develop & Build GatsbyJS static sites within Docker](https://github.com/aripalo/gatsby-docker/)
+
 ## Videos
 
 * [Static Site Generation with Gatsby.js v0 — Scott Nonnenberg](https://blog.scottnonnenberg.com/static-site-generation-with-gatsby-js/)