Set CI to upload rendered documentation

[arthurp]

Uploading the rendered documentation of the project to a website provides something to link and is easier to read than documentation in the code. Ideally this would upload for PRs as well to make it easier to check the documentation or link to documentation that isn't yet merged. PR and main head documentation should be discarded after a while with only releases kept indefinitely.

Implementation

• Setup some hosting for this. Presumably on some UTCS machine with web hosting.
• Re-enable the documentation generation in CI (it is already in there, just disabled).