Fix a few issues.

-single-dash => --double-dash for a few flags, and also there was a missing "B", as in "Container B".

Docker-DCO-1.1-Signed-off-by: Nathan LeClaire <nathan.leclaire@gmail.com> (github: nathanleclaire)
Merge pull request #5952 from nathanleclaire/patch-2

Fix a few issues.