Create project LICENSE file and update any related documentation accordingly

[cbj4074]

I've created this issue mostly to initiate discussion regarding which license might work best for our use-case.

Presently, the two contenders with regard to a license that covers project documentation are:

• GNU GDFL: https://www.gnu.org/licenses/fdl-1.3.en.html
• Creative Commons BY: https://creativecommons.org/licenses/by/4.0/

https://en.wikipedia.org/wiki/GNU_Free_Documentation_License provides information about the differences between the two, where they are incompatible, criticisms of the former, etc., and is worth reviewing.

The CC-BY license is considerably simpler, but that doesn't necessarily mean it's preferable.

I'd appreciate any feedback with regard to concerns around using one license versus the other, in the context of this project's documentation.

While there is no immediate rush, at some point, it will be appropriate to choose a license to govern the works contained within this repository.