Add release notes for #2813 and tweak grammar of release notes for #2616.
Add release notes for #2813 and tweak grammar of release notes for #2616.

sasha0/django-oscar,solarissmoke/django-oscar,solarissmoke/django-oscar,django-oscar/django-oscar,django-oscar/django-oscar,django-oscar/django-oscar,solarissmoke/django-oscar,sasha0/django-oscar,django-oscar/django-oscar,sasha0/django-oscar,solarissmoke/django-oscar,sasha0/django-oscar