title: How to set "concurency=X" for limiting number of concurrent workflows in Github Actions?
body: <p>I'm looking for a way to use concurrency != 1, i.e. I want to limit the number of concurrent workflows to 2 for example.
  It seems to be a very trivial feature for CI platform, but I couldn't find a way to do that in Github Actions.</p>
  <p>Thanks,
  Vitaly</p>