doc: shift doc to Rio

What

Drop the doc for Quebec and install the doc of Rio as the active protocol.

Why

Rio will probably be adopted around May 1st.

How

Follow meta-issue #2170.

Manually testing the MR

Check the doc artifact.

Check the CI.

Note for reviewers: the changes have been split on purpose in several commits, for grouping aside purely technical changes (removing folder docs/quebec, redirecting labels to the active protocol), so reviewers can safely look at the others, much smaller commits dealing with contents.

Checklist

• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR