Missing OS_EXTGW_ID in OpenStack Docs
Missing OS_EXTGW_ID in OpenStack Docs

This commit adds a note about the requirement for the OS_EXTGW_ID
environment variable in order to run the OpenStack Provider acceptance
tests.

haxorof/terraform-provider-openstack,haxorof/terraform-provider-openstack,haxorof/terraform-provider-openstack