Title version with more info

• One wants to specify a http link for a version (as in keepachangelog)
• One wants to have an ISO date added after the version (as in keepachangelog)
• One wants to add arbitrary markdown under the version title

To address all those, the following parameters should be added:

• --link=
• --subtitle=
• --with-date

Each markdown title should also be preceded with a blank line to be compliant with all markdown flavors.

Ideas proposed from Dorian Turba and others at PyconFr 2025