I don't think it's either. "Scaling" refers to growing the amount of compute power you are using. This change falls into a different bucket, which is making more efficient use of the compute that's already available.
If they are running multiple Docker containers, the improved efficiency would allow them to run more containers per host computer. Maybe that's what they meant, although it's not really horizontal scaling either.
If they are running multiple Docker containers, the improved efficiency would allow them to run more containers per host computer. Maybe that's what they meant, although it's not really horizontal scaling either.