docker: include jquery from secured link

Previous version included jquery from a non-secured URL (http), which is
problematic in case the engine is working with a secured URL (https), so
making https the default, and adding an installation note to change that
in case needed.

Change-Id: I06bd1665ab6c3217c101e6b517ea2bd3b397c052
Signed-off-by: Oved Ourfali <oourfali@redhat.com>