Use the generate.sh script instead of md2man directly.
Update Dockerfile for generating man pages.
Signed-off-by: Daniel Nephin <dnephin@docker.com>
(cherry picked from commit 00a8a40398263429f99b1a5f0be59048e1c6f38d)
Signed-off-by: Tibor Vass <tibor@docker.com>