From the GitHub page, it looks like Divio is actually a fork of Diátaxis.
divio/diataxis-documentation-framework is forked from evildmp/diataxis-documentation-framework, and evildmp is Daniele Procida, the creator of the latter repository and the maintainer of diataxis.fr.
But according to the network graph on GitHub, Diataxis seems to be more active, although both of them still receive updates.