[Referee invitations] Add link to journals acceptance criteria in referee invitation emails
Invited referees should be pointed toward the Acceptance Criteria (AC) of the journals where a submission could potentially be published. The set of journals would be given by the target journal, but also other journals to which the submission could be transferred. For example, submissions to SP Phys. should have links to the AC of both SP Phys. and SP Phys. Core, https://scipost.org/SciPostPhys/about#criteria and https://scipost.org/SciPostPhysCore/about#criteria.
If no transfer is possible (e.g., Proceedings, Lecture Notes), a single link is sufficient.
The links should be present in all types of refereeing invitation emails: for referees with an existing SciPost account (email subject: SciPost: refereeing request), those without one (email subject: SciPost: refereeing and registration invitation) and reminders (email subjects SciPost: refereeing request reminder; SciPost: reminder (refereeing request and registration invitation)).
[Specific phrasing can be discussed]