Updated DEPLOYMENT (markdown)

DEPLOYMENT.md

@@ -4,6 +4,7 @@ Follow this steps to deploy a new version of Rambox:
 
 1. Define Rambox version editing **app/package.json** and **appveyor.yml**.
 1. Define Electron version in **package.json** and Travis CI Environment Variables.
+1. Define **electron-builder** version in **package.json**.
 2. Once commited all with Github Desktop Client, clean and build the project:
 
  > `npm run sencha:clean`