Add additional license info

[lukefretwell]

via @mannyb16:

Licensing assumes – GPL v.3 would work for all projects. We may need different licenses depending on the type of project and contribution for instance, documentation may require a Creative Commons license. Additionally, there may be license compatibility issues that state entities may need to address. We could consider specifying certain types of licenses e.g. GPL v.2, GPL v.3, Apache, Creative Commons, instead of designating a single license.

• add to playbook: https://codecagov-playbook.readthedocs.io/en/latest/README/
• add to doc: https://docs.google.com/document/d/1hXYzV_KW49epVuj9EuUGP1hNNARRMf_yVi1Uz5XX_oI/edit?usp=sharing