Clarify field docs on the state of removed fields.
Clarify field docs on the state of removed fields.

mlavin/django-selectable,mlavin/django-selectable,affan2/django-selectable,makinacorpus/django-selectable,affan2/django-selectable,mlavin/django-selectable,makinacorpus/django-selectable,affan2/django-selectable