instructor-customizable message in ISLE email when users are added

[gweinberg]

Problem

When we add users to a cohort, ISLE generates an email to those users.
Currently, that email is not customizable by the instructor (as far as I know).

Solution

I would like the ability to customize that email (so that I could, for instance, tell students to see such-and-such document on Canvas in such-and-such location for more info/instructions, and also so I could remind different cohorts of the day/time/location of their labs, etc)

Alternatives

No response

Additional context

None.