project: remove dox dependency (security issues, hard-to-upgrade)

[x1B]

The laxar-dox doc generator uses a very outdated version of dox that relies on outdated dependencies.
This dependency is responsible for almost all security audit issues reported in the repo.

Since upgrading would not be worth the effort, I'll drop the dependency for now.
This means that going forward, any API changes will need to be reflected in the docs manually.