Merge pull request #906 from ansonlowzf/patch-1

add to install theme-ui

Author: hasparus

packages/docs/src/pages/getting-started/gatsby.mdx

@@ -7,7 +7,7 @@ title: Getting Started with Gatsby
 To use Theme UI with [Gatsby][], install and use [`gatsby-plugin-theme-ui`](/packages/gatsby-plugin).
 
 ```sh
-npm i gatsby-plugin-theme-ui
+npm i theme-ui gatsby-plugin-theme-ui
 ```
 
 Add the plugin to your `gatsby-config.js`.