Update README.md

Author: colebemis

README.md

@@ -4,7 +4,7 @@ ESLint rules for Primer React
 
 ## Installation
 
-1. Assuming you already have [ESLint](https://www.npmjs.com/package/eslint) installed, run:
+1. Assuming you already have [ESLint](https://www.npmjs.com/package/eslint) and [Primer React](https://github.com/primer/react) installed, run:
 
    ```shell
    npm install --save-dev eslint-plugin-primer-react