As an editor, I want a reminder to go to wagtail backend if I want to edit content if I forget and log into the django admin, so that I can easily get to the right place to edit content.

[rlskoeser]

Is your feature request related to a problem? Please describe.
Sometimes people still forget the url they should be using to edit site content.

Describe the solution you'd like
Add a prominent notice on the django admin dashboard linking to wagtail admin for content editing.

Describe alternatives you've considered
I don't think we should shut down the django admin entirely, in case we need to edit any of the lingering things that are there and not in wagtail. But we could move it to a different url and set the admin url to redirect to the cms url.

Additional context
Adding a notice should be easy to do — just extend the admin index template.