Update CHANGELOG for VM IP allocation by pool
Update CHANGELOG for VM IP allocation by pool

Reflects changes in
https://github.com/alphagov/vcloud-launcher/pull/38/files.

UKHomeOffice/vcloud-launcher,gds-operations/vcloud-launcher,UKHomeOffice/vcloud-launcher,gds-operations/vcloud-launcher,UKHomeOffice/vcloud-launcher,gds-operations/vcloud-launcher