message: docs: document supported operating systems and versions
diff: @@ -20,6 +20,17 @@ was written correctly and much more.
  ![Etcher](https://raw.githubusercontent.com/resin-io/etcher/master/screenshot.png)
  +Supported Operating Systems
  +---------------------------
  +
  +- Linux (most distros)
  +- macOS 10.9 and later
  +- Microsoft Windows 7 and later
  +
  +Note that Etcher will run on any platform officially supported by
  +[Electron][electron]. Read more in their
  +[documentation][electron-supported-platforms].
  +
  Installers
  ----------
  @@ -70,6 +81,8 @@ Etcher is free software, and may be redistributed under the terms specified in
  the [license].
  [etcher]: https://etcher.io
  +[electron]: http://electron.atom.io
  +[electron-supported-platforms]: http://electron.atom.io/docs/tutorial/supported-platforms/
  [SUPPORT]: https://github.com/resin-io/etcher/blob/master/SUPPORT.md
  [CONTRIBUTING]: https://github.com/resin-io/etcher/blob/master/docs/CONTRIBUTING.md
  [CLI]: https://github.com/resin-io/etcher/blob/master/docs/CLI.md
  