slapos.cfg.example: add URLs with dash

also remove lab.node.vifib.com old URL. The URLs we support for gitlab
are:
 * lab.nexedi.com
 * lab.nxdcdn.com
 * lab.nexedi.cn
5 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
failed SlapOS-Master.UnitTest-Master

02:41:16

failed SlapOS.Eggs.UnitTest-Master.Python2

00:26:15

failed SlapOS.Eggs.UnitTest-Master.Python3

00:19:45

passed SlapOS.Eggs.UnitTest-Master.Python2

00:43:14

failed SlapOS.Eggs.UnitTest-Master.Python3

00:17:24