Better explaining FQDN request

Adding a more meaningful text to better explain
what host it refers asking a FQDN

Change-Id: I1548ad11bc4699b50747ae6978a58874287059f2
Signed-off-by: Simone Tiraboschi <stirabos@redhat.com>
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1069945