Update demo.rst
Update demo.rst

With requirements file of django >= 1.7.0, change command of `syncdb` to `migrate` (`syncdb` is deprecated).
kdzch/django-rest-auth,caruccio/django-rest-auth,philippeluickx/django-rest-auth,aexeagmbh/django-rest-auth,maxim-kht/django-rest-auth,maxim-kht/django-rest-auth,Tivix/django-rest-auth,caruccio/django-rest-auth