[1.8.x] Fixed #25082 -- Documented where to register system checks.
[1.8.x] Fixed #25082 -- Documented where to register system checks.

Backport of 074a82f49b1443e66885ea861bbd2d2cb04af43e from master

h4r5h1t/django-hauthy,h4r5h1t/django-hauthy,h4r5h1t/django-hauthy,h4r5h1t/django-hauthy