Update PubSub Raw doc (#4659)

* Update pubsub-raw.md

Updating Raw PubSub doc to be more specific about content type and delivery details.

Signed-off-by: Alice Gibbons <[email protected]>

* Update daprdocs/content/en/developing-applications/building-blocks/pubsub/pubsub-raw.md

Signed-off-by: Mark Fussell <[email protected]>

---------

Signed-off-by: Alice Gibbons <[email protected]>
Signed-off-by: Mark Fussell <[email protected]>
Co-authored-by: Mark Fussell <[email protected]>

Author: alicejgibbons

daprdocs/content/en/developing-applications/building-blocks/pubsub/pubsub-raw.md

@@ -6,7 +6,7 @@ weight: 2200
 description: "Learn when you might not use CloudEvents and how to disable them."
 ---
 
-When adding Dapr to your application, some services may still need to communicate via pub/sub messages not encapsulated in CloudEvents, due to either compatibility reasons or some apps not using Dapr. These are referred to as "raw" pub/sub messages. Dapr enables apps to [publish and subscribe to raw events]({{< ref "pubsub-cloudevents.md#publishing-raw-messages" >}}) not wrapped in a CloudEvent for compatibility.
+When adding Dapr to your application, some services may still need to communicate via pub/sub messages not encapsulated in CloudEvents, due to either compatibility reasons or some apps not using Dapr. These are referred to as "raw" pub/sub messages. Dapr enables apps to [publish and subscribe to raw events]({{< ref "pubsub-cloudevents.md#publishing-raw-messages" >}}) not wrapped in a CloudEvent for compatibility and to send data that is not JSON serializable.
 
 ## Publishing raw messages
 
@@ -105,13 +105,15 @@ $app->run(function(\DI\FactoryInterface $factory) {
 
 ## Subscribing to raw messages
 
-Dapr apps are also able to subscribe to raw events coming from existing pub/sub topics that do not use CloudEvent encapsulation.
+Dapr apps can subscribe to raw messages from pub/sub topics, even if they weren’t published as CloudEvents. However, the subscribing Dapr process still wraps these raw messages in a CloudEvent before delivering them to the subscribing application.
 
 <img src="/images/pubsub_subscribe_raw.png" alt="Diagram showing how to subscribe with Dapr when publisher does not use Dapr or CloudEvent" width=1000>
 
 ### Programmatically subscribe to raw events
 
-When subscribing programmatically, add the additional metadata entry for `rawPayload` to allow the subscriber to receive a message that is not wrapped by a CloudEvent. For .NET, this metadata entry is called `isRawPayload`.
+When subscribing programmatically, add the additional metadata entry for `rawPayload` to allow the subscriber to receive a message that is not wrapped by a CloudEvent. For .NET, this metadata entry is called `isRawPayload`. 
+
+When using raw payloads the message is always base64 encoded with content type `application/octet-stream`.
 
 {{< tabs ".NET" "Python" "PHP" >}}
 
@@ -242,4 +244,4 @@ scopes:
 - Learn more about [publishing and subscribing messages]({{< ref pubsub-overview.md >}})
 - List of [pub/sub components]({{< ref supported-pubsub >}})
 - Read the [API reference]({{< ref pubsub_api.md >}})
-- Read the .NET sample on how to [consume Kafka messages without CloudEvents](https://github.com/dapr/samples/pubsub-raw-payload)
+- Read the .NET sample on how to [consume Kafka messages without CloudEvents](https://github.com/dapr/samples/pubsub-raw-payload)