Document how to replay documents into new callbacks (e.g. how to replot a scan)

[Tom-Willemsen]

Description of work

• Documents how to replot a scan
• More generally, how to replay a set of documents from a previous scan into an arbitrary new set of callbacks; which may also include fitting or other callbacks.

Ticket

Closes #156

Labels

documentation

Acceptance criteria

• Pull request title is understandable for a user (e.g. scientist) reading the release notes. The PR title should be a short description of the change from a user perspective.
• Pull request has appropriate labels for automatic release-notes generation
• A previously performed scan can be replotted by following the instructions on the new documentation page

Documentation

See PR

[rerpha]

we should link to this in docs/callbacks/plotting i'd say.