Copyedit builds

Trying again since the first PR seems to have been lost.

Docker-DCO-1.1-Signed-off-by: Fred Lifton fred.lifton@docker.com (github: fredlf)
Fixed the capitalization issues, thanks for that.

I referred to repo as the context here after consultation with @SvenDowideit . He and I agree that the usage of this term is rather squishy and needs to be tightened up. That is beyond the scope of this immediate revision.

Added "automatically". Good call, thanks.

Added "automated" to modify "images," though the term appears in only one other document (search) in the docs.