fixed version in readme

Author: agusmakmun

README.rst

@@ -11,7 +11,7 @@ martor |pypi version|
 .. image:: https://img.shields.io/pypi/pyversions/martor.svg
    :target: https://pypi.python.org/pypi/martor
 
-.. image:: https://img.shields.io/badge/Django-1.8%20%3E=%203.1-green.svg
+.. image:: https://img.shields.io/badge/Django-1.8%20%3E=%203.0-green.svg
   :target: https://www.djangoproject.com
 
 .. image:: https://travis-ci.org/agusmakmun/django-markdown-editor.svg?branch=master