Update usage.rst
Update usage.rst

Fixed a typo:  tekst --> text

--Fred
Felix-neko/django-tinymce,affan2/django-tinymce,lutoma/django-tinymce,aljosa/django-tinymce,joelburton/django-tinymce,leture/django-tinymce,affan2/django-tinymce,lutoma/django-tinymce,lutoma/django-tinymce,leture/django-tinymce,joelburton/django-tinymce,sandow-digital/django-tinymce,aljosa/django-tinymce,agushuley/gu-django-tinymce,Felix-neko/django-tinymce,joelburton/django-tinymce,sandow-digital/django-tinymce,lutoma/django-tinymce,affan2/django-tinymce,Felix-neko/django-tinymce,sandow-digital/django-tinymce,aljosa/django-tinymce,agushuley/gu-django-tinymce,aljosa/django-tinymce,joelburton/django-tinymce,agushuley/gu-django-tinymce,leture/django-tinymce,sandow-digital/django-tinymce,affan2/django-tinymce,agushuley/gu-django-tinymce,Felix-neko/django-tinymce,leture/django-tinymce