Added Django REST Framework usage docs (#238)

* Added Django REST Framework usage notes

* Better instructions

Based on discussion in #238 (comment)

README.rst

@@ -291,6 +291,12 @@ occurs, and automatic conversion can hide bugs. Also, with automatic conversion
 you lose some properties like commutativity (``A + B == B + A``) due to
 conversions happening in different directions.
 
+Usage with Django REST Framework
+--------------------------------
+
+For MoneyFields to automatically work with Django REST Framework, make sure
+that ``djmoney`` is in the ``INSTALLED_APPS`` of your ``settings.py``.
+
 Known Issues
 ------------
 Updates to a model form will not save in Django 1.10.1.  They will save in 1.10.0 and is expected to be fixed in Django 1.10.2.