Need to propagate the Apache 2.0 license from Pace

[bensonr]

Is your feature request related to a problem? Please describe.
The issue is a lack of licensing. We created this project by splitting the logic off from the existing NOAA-GFDL Pace project and need to respect the original ai2cm license specification.

Describe the solution you'd like
Inclusion of the Apache 2.0 license text from NOAA-GFDL Pace project.

Describe alternatives you've considered
N/A

Additional context
N/A