Fix installation instruction of `aswcli`
Fix installation instruction of `aswcli`

The awscli is not a cask application. It's a plain homebrew package.
retronym/scala-jenkins-infra,SethTisue/scala-jenkins-infra,scala/scala-jenkins-infra,SethTisue/scala-jenkins-infra,adriaanm/scala-jenkins-infra,DarkDimius/scala-jenkins-infra,adriaanm/scala-jenkins-infra,adriaanm/scala-jenkins-infra,DarkDimius/scala-jenkins-infra,DarkDimius/scala-jenkins-infra,lrytz/scala-jenkins-infra,lrytz/scala-jenkins-infra,scala/scala-jenkins-infra,retronym/scala-jenkins-infra,lrytz/scala-jenkins-infra,retronym/scala-jenkins-infra,SethTisue/scala-jenkins-infra