The installer completed page now contains information on next steps, so is more useful than the intro

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@docker.com> (github: SvenDowideit)
Merge pull request #6855 from SvenDowideit/update-osx-installer-image-to-show-final-page

The installer completed page now contains information on next steps, so ...