document the cherry-pick process I'm using to make docs updates

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@docker.com> (github: SvenDowideit)
Adding Docs Deploy process to Docs ReadMe

Additions and revisions to Sven's cherry-pick process doc.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)
Merge pull request #7850 from fredlf/add_cherrypick_process

Add cherrypick process