title: Missing .env in Vue CLI after run build
body: <p>I'm building an app using Vue CLI 3. 
  I've included <code>.env</code> in my project and everything works fine. </p>
  
  <p>But when i'm building the app for production via <code>npm run build</code> there is no <code>.env</code> file in my <code>dist</code> folder, so i can't change my environmental variables in production server.
  Any solution or it's just fine?</p>