Add --dryrun to allow testing to the docs-release site, and then fix the...

... double dollar mistake

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@docker.com> (github: SvenDowideit)

@fredlf @jamtur01 @tianon 

closes #docker/docker-index/1652
"sendin" ? :smile: