Minor placeholder doc tweaks.
Minor placeholder doc tweaks.

respondcreate/django-versatileimagefield,WGBH/django-versatileimagefield,theskumar/django-versatileimagefield,theskumar/django-versatileimagefield,WGBH/django-versatileimagefield,respondcreate/django-versatileimagefield,WGBH/django-versatileimagefield,theskumar/django-versatileimagefield,respondcreate/django-versatileimagefield