title: next build command is not ignoring *.stories.tsx files
body: <p>I am trying to build <code>nextjs</code> project which has <code>[componentName].stories.tsx</code> side by side with component itself. Running <code>next build</code> fails because of typescript errors in these stories. I want next to ignore <code>storybook</code> files. Is it possible and if yes how do I do it ?</p>