Fix typo in description ("an" :arrow_right: "a")

README.md

@@ -4,7 +4,7 @@
 
 This is a minimal Electron application based on the [Quick Start Guide](http://electron.atom.io/docs/latest/tutorial/quick-start) within the Electron documentation.
 
-An basic Electron application needs just these files:
+A basic Electron application needs just these files:
 
 - `index.html` - A web page to render.
 - `main.js` - Starts the app and creates a browser window to render HTML.