Hi folks, many thanks for this great framework!!!

Description

The source code snippets shown in the API documentation are great, but up not now not adaptable. I would like to add source code snippets for different languages or for using the interface via a special wrapper library, which is used in our project to route requests depending on being on a productive or a staging system.

To have a chance to inject a modified version of DocumentationRenderer, the parameter renderer_classes has been added to documentation.include_docs_urls(). Now i can e.g. reduce
the number of displayed source code languages (and modify the ordering) like this:

from rest_framework.renderers import DocumentationRenderer, CoreJSONRendererclass MyDocumentationRenderer(DocumentationRenderer):    languages = ['python', 'shell']renderer_classes = [MyDocumentationRenderer, CoreJSONRenderer]urlpatterns = [                                                                                                    url(r'^docs/', include_docs_urls(title='My API', renderer_classes=renderer_classes)),       :

To make this work some of the HTML templates have been adapted as well.

By adding new language names and providing the appropriate templates, it is now even possible to add new language snippets to the API documentation.

What do you think?

Thanks and Regards,

Georg