Documentation/configure-kubectl: s/vagrant/default/
Documentation/configure-kubectl: s/vagrant/default/

Remove the overly specific mentions of "vagrant" in resource names in this general-purpose document. Specific vagrant documents exist.

Fixes https://github.com/coreos/coreos-kubernetes/issues/124
four43/coreos-kubernetes,joshix/coreos-kubernetes,amarruedo/coreos-kubernetes,joshix/coreos-kubernetes,cedbossneo/coreos-kubernetes,limres/coreos-kubernetes,colhom/coreos-kubernetes,four43/coreos-kubernetes,turbonomic/coreos-kubernetes,danielfm/coreos-kubernetes,limres/coreos-kubernetes,bcwaldon/coreos-kubernetes,endocode/coreos-kubernetes,colhom/coreos-kubernetes,turbonomic/coreos-kubernetes,chen-anders/coreos-kubernetes,bnea-engineering/coreos-kubernetes,IDKA/coreos-kubernetes,IDKA/coreos-kubernetes,coreos/coreos-kubernetes,IDKA/coreos-kubernetes,colhom/coreos-kubernetes,endocode/coreos-kubernetes,amarruedo/coreos-kubernetes,chen-anders/coreos-kubernetes,ah45/coreos-kubernetes,cedbossneo/coreos-kubernetes,bcwaldon/coreos-kubernetes,danielfm/coreos-kubernetes,bnea-engineering/coreos-kubernetes,amarruedo/coreos-kubernetes,limres/coreos-kubernetes,ah45/coreos-kubernetes,bnea-engineering/coreos-kubernetes,bcwaldon/coreos-kubernetes,four43/coreos-kubernetes,cedbossneo/coreos-kubernetes,chen-anders/coreos-kubernetes,amarruedo/coreos-kubernetes,endocode/coreos-kubernetes,danielfm/coreos-kubernetes,coreos/coreos-kubernetes,ah45/coreos-kubernetes,turbonomic/coreos-kubernetes