message: doc(environments): clarify acceptable version for feature
diff: @@ -96,6 +96,10 @@ As of `@ionic/app-scripts@3.2.0` you can also use
  [environment variables directly in your source code](https://github.com/ionic-team/ionic-app-scripts#environments)
  and they will be replaced at build time so that you can customize your code based on the environment.
  +<blockquote>
  + <p><b>Note:</b>`@ionic/app-scripts` is only for use with Ionic Framework v3 applications. The above does not apply to other versions.</p>
  +</blockquote>
  +
  For example:
  ```typescript
  