Removed unnecessary build step

The building/testing instructions said to run "npm run build", which doesn't exist

Author: JamesMessinger

README.md

@@ -138,10 +138,7 @@ To build/test the project locally on your computer:
 2. __Install dependencies__<br>
 `npm install`
 
-3. __Run the build script__<br>
-`npm run build`
-
-4. __Run the tests__<br>
+3. __Run the tests__<br>
 `npm test`