New screenshots and revisions to builds.md

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)
Fix typos

Docker-DCO-1.1-Signed-off-by: Bryan Bess <squarejaw@bsbess.com> (github: squarejaw)
Merge pull request #6948 from squarejaw/master

Fix typos
Merge pull request #6945 from fredlf/copyedit-builds

New screenshots and revisions to builds.md