docs/google: fix code blocks

merge to docs branch from #6241

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)

(cherry picked from commit e2119f3050b225ccaf25990e5d6714dae2de7afe)

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)