Docs/Proto: port AI doc from Paris to Alpha

Port AI doc to Alpha:

• !13169 (merged) (fixes #7226 (closed))
• !13105 (merged) (fixes #7193 (closed))

The files were updated as follows:

• copy from paris/ to alpha/
• replace _paris with _alpha
• remove extra tags
• docs/alpha/adaptive_issuance.rst: apply changes from !12689 (merged)
• docs/alpha/consensus.rst: apply changes from !12861 (merged)

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• 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).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR