chore(docs): Correct peerDeps for Gatsby integration (#791)

Co-authored-by: mattcompiles <[email protected]>

Author: LekoArts

site/docs/integrations/gatsby.md

@@ -10,7 +10,7 @@ A plugin for integrating vanilla-extract with [Gatsby](https://www.gatsbyjs.com)
 ## Installation
 
 ```bash
-npm install gatsby-plugin-vanilla-extract
+npm install gatsby-plugin-vanilla-extract @vanilla-extract/babel-plugin @vanilla-extract/css @vanilla-extract/webpack-plugin
 ```
 
 ## Setup