Rocqnavi: 📝 Use Rocqnavi's development HEAD instead of the released version

[yoshihiro503]

Motivation for this change

Documentation generation (make html) now uses the latest development version of Rocqnavi, instead of the latest released version. This lets us use new Rocqnavi features/fixes before they're officially released.

Checklist

• appended entries in the relevant sections of CHANGELOG_UNRELEASED.md

• added corresponding documentation in the headers

Reference: How to document

Merge policy

As a rule of thumb:

• PRs with several commits that make sense individually and that
  all compile are likely to be merged as they are into master.
• PRs with disorganized commits are very likely to be squash-rebased.

Reminder to reviewers

• Read this Checklist
• Put a milestone if possible
• Check labels