An idea to support per-method serializer in a Viewset

Nobody has claimed this yet.

I've implemented something like this on my fork

```
from my_serializers import PasswordSerializer
from rest_framework_docs.utils import func_serializer

class UserViewSet(viewsets.ViewSet):

@func_serializer(serializer_class=PasswordSerializer)
@detail_route(methods=['post'])
def set_password(self, request, pk=None):
serializer = PasswordSerializer(data=request.data)
```

I wonder if you are keen on extending your library with something like this? I think it's a handy feature.

The downside of this is that we have to change application code to support documentation generation. Another approach is to use docstring, something like

```

class UserViewSet(viewsets.ViewSet):

@detail_route(methods=['post'])
def set_password(self, request, pk=None):
"""
:func_serializer: my_serializers.PasswordSerializer
"""
serializer = PasswordSerializer(data=request.data)
```

I think I like the first approach better.

Start by reviewing the library's current documentation-generation entry points for ViewSet methods and how serializers are discovered. Compare the proposed decorator and docstring approaches, then define the supported per-method behavior and verify that generated API documentation uses the selected serializer for each method.

Written by the indexing model from the issue text.