python-novaclient - en to en_GB translation catalogue (2 entries)

en: **auto**: This tells the Compute service to automatically allocate a network for the project if one is not available and then associate an IP from that network with the server. This is the same behavior as passing nics=None before the 2.37 microversion.
en_GB: **auto**: This tells the Compute service to automatically allocate a network for the project if one is not available and then associate an IP from that network with the server. This is the same behaviour as passing nics=None before the 2.37 microversion.

en: --security_groups replaced by --sercurity-groups
en_GB: --security_groups replaced by --security-groups
