When exporting data from [an insight](https://app.posthog.com/insights/oVHjTLUD), the action names weren't exported, making the CSV a little hard to follow.

As a user, I'd expect to see the same data in the export as I see in the table in-app.

<img width="1012" alt="image" src="https://user-images.githubusercontent.com/154479/166958828-9b3add76-633b-4f1d-ad2b-cf1ea2888b95.png">

posthog/api/insight.py
try:
            before_update = Insight.objects.get(pk=instance.id)
        except Insight.DoesNotExist:
            before_update = None
        
        validated_data["is_sample"] = False
        if validated_data.keys() & Insight.MATERIAL_INSIGHT_FIELDS:
            instance.last_modified_at = now()
            instance.last_modified_by = self.context["request"].user