Deploy documentation online.

[iago-lito]

Github offers to host documentation online under the form of a website.

• Follow gh-pages instructions to deploy documentation online as part of some CI job triggered on pushes to dev and/or main?
• Update urls in the docs so they correctly point to help pages hosted on github. (3477e6b)
• Enforce that the success of this deployment be required prior to merging new commits into dev. This would make the checks too heavy. Instead, and for now, just make sure that the docs do build prior to mergin dev into main.

Currently blocked on #105.

[iago-lito]

Closed by #146.