Mention django-jsonfield in the README.rst.
Mention django-jsonfield in the README.rst.

rolandgeider/OpenSlides,jwinzer/OpenSlides,normanjaeckel/OpenSlides,FinnStutzenstein/OpenSlides,emanuelschuetze/OpenSlides,FinnStutzenstein/OpenSlides,FinnStutzenstein/OpenSlides,tsiegleauq/OpenSlides,boehlke/OpenSlides,jwinzer/OpenSlides,normanjaeckel/OpenSlides,ostcar/OpenSlides,rolandgeider/OpenSlides,boehlke/OpenSlides,CatoTH/OpenSlides,jwinzer/OpenSlides,OpenSlides/OpenSlides,tsiegleauq/OpenSlides,CatoTH/OpenSlides,normanjaeckel/OpenSlides,OpenSlides/OpenSlides,emanuelschuetze/OpenSlides,jwinzer/OpenSlides,ostcar/OpenSlides,rolandgeider/OpenSlides,CatoTH/OpenSlides,CatoTH/OpenSlides,normanjaeckel/OpenSlides,emanuelschuetze/OpenSlides,jwinzer/OpenSlides,ostcar/OpenSlides,emanuelschuetze/OpenSlides,boehlke/OpenSlides,FinnStutzenstein/OpenSlides,tsiegleauq/OpenSlides,boehlke/OpenSlides