fixing links to d4mac and d4win
updates per @Sven and @theJeztah, fixing links, typos, menu definitions, etc.
updates per Sven's comments in the PR
removed duplicate line in tutorials menu.md
Signed-off-by: Victoria Bialas <victoria.bialas@docker.com>
fixing links after moving surfacing tutorials
fixing more links for the newly located tutorials
WIP: merging 3 getting started tutorials into one to cover all platforms, added new files
fixing broken images and links in 3-in-1 getting started, re-wrote story flow, linked to Toolbox, d4mac,d4win
Signed-off-by: Victoria Bialas <victoria.bialas@docker.com>
