Add Yarn warning to update instructions.

Author: handleyj

README.md

@@ -49,6 +49,8 @@ If your theme uses TypeScript, you'll need to run a second command (`create-reac
 
 `npm install react-scripts@latest`
 
+**Important note for Yarn users: be sure to use `yarn add` instead of `npm install` in the above commands.**
+
 ## Coding with React
 
 ### React Tutorials

package.json

@@ -1,6 +1,6 @@
 {
     "name": "create-react-wptheme",
-    "version": "2.1.8-wptheme-2.2.2",
+    "version": "2.1.8-wptheme-2.2.3",
     "description": "Create React WP themes with no build configuration.",
     "main": "index.js",
     "scripts": {