There is a contradiction about which Creative Commons license is offered: * The words say [Creative Commons Attribution-NonCommercial-ShareAlike 4.0](https://github.com/active-calculus/active-calculus-vector/blob/58c43b955c1dc378689610e93f63d768e766d22a/source/colophon.ptx#L21) * The icon says [CC BY-SA 4.0](https://github.com/active-calculus/active-calculus-vector/blob/58c43b955c1dc378689610e93f63d768e766d22a/source/colophon.ptx#L18) Please resolve the inconsistency.