pools: add doc
pools: add doc

Signed-off-by: Emilien Macchi <d605a501dec15c980af71d9dfebf4b595ab6da1f@enovance.com>

goneri/puppet-openstack-cloud,gwdg/puppet-openstack-cloud,redhat-cip/puppet-openstack-cloud,gwdg/puppet-openstack-cloud,goneri/puppet-openstack-cloud,gwdg/puppet-openstack-cloud,redhat-cip/puppet-openstack-cloud,gwdg/puppet-openstack-cloud,redhat-cip/puppet-openstack-cloud,Prophidys/puppet-openstack-cloud,Prophidys/puppet-openstack-cloud,Prophidys/puppet-openstack-cloud