packaging: Remove extra quote from remote DB creation instructions

When using a remote DB, engine-setup prompts the user the right way to
create a DB.
In those instructions, the username was surrounded by quotes, which is
unneeded.

Change-Id: If34b74c1c84168f018c6a748eb1519d73af8ac26
Signed-off-by: Ofer Schreiber <oschreib@redhat.com>
Bug-Url: https://bugzilla.redhat.com/1040572