Minor formatting change to CONTRIBUTING.rst
Minor formatting change to CONTRIBUTING.rst

Removed numbered list formatting from single
item list.

Change-Id: Ifc9722e620eefc2580da921bc0c3084b9c25142c

coolsvap/kolla,intel-onp/kolla,openstack/kolla,intel-onp/kolla,GalenMa/kolla,dardelean/kolla-ansible,mandre/kolla,openstack/kolla,dardelean/kolla-ansible,mrangana/kolla,stackforge/kolla,coolsvap/kolla,dardelean/kolla-ansible,rahulunair/kolla,mandre/kolla,stackforge/kolla,rahulunair/kolla,GalenMa/kolla,mrangana/kolla,nihilifer/kolla,stackforge/kolla,nihilifer/kolla,coolsvap/kolla,mandre/kolla