cli: ovirt-shell misleading help for command "connect"(#907943)

ovirt-shell does not allow the use of show command before being
connected to the engine. The help connect message however has
refernce to see show command for more details.

This patch corrects the help message for connect by removing the
refernce to the show command

Change-Id: Ifcea649dcd44c87c9f9dff0fa4b65ac9c2449c32
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=907943
Signed-off-by: Ravi Nori <rnori@redhat.com>