Context

Closes #2537 (closed) by documenting the remaining interfaces of lib_protocol (Alpha).

Checklist

Document the interface of any function added or modified (see the coding guidelines): no function added.
Document any change to the user interface, including configuration parameters (see node configuration): no change to the user interface.
Provide automatic testing (see the testing guide): no implementation, thus no testing required.
For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else): no new features.
Select suitable reviewers using the Reviewers field below.
Select as Assignee the next person who should take action on that MR

Edited Apr 26, 2022 by Nicolas Ayache