docker-edge: mark discontinued as Edge channel has been removed (#10806)
docker-edge: mark discontinued as Edge channel has been removed (#10806)

* docker-edge: mark discontinued as Edge channel has been removed

* Update docker-edge.rb

Co-authored-by: Miccal Matthews <a53b0df86fcdccc56e90f3003dd9230c49f140c6@gmail.com>
404NetworkError/homebrew-versions,pkq/homebrew-versions,mahori/homebrew-cask-versions,404NetworkError/homebrew-versions,pkq/homebrew-versions