Replace Cartesia references (#1631)

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: Kapil Gowru <[email protected]>
Co-authored-by: Devin Logan <[email protected]>

Author: 3 people

fern/products/api-def/ferndef-pages/websockets.mdx

@@ -81,16 +81,8 @@ A `channel` is defined by the following fields:
 
 Fern renders a unique reference page for WebSockets. The **Handshake** section outlines the protocol for connecting with the server, while the **Send** and **Receive** sections outline the message schemas that can be sent between the client and server. 
 
-<Frame caption="Cartesia's WebSocket Reference page">
+Users can connect to and use WebSockets from right within the API Reference (check one of Hume's WebSockets [here](https://dev.hume.ai/reference/text-to-speech-tts/stream-input)). 
+
+<Frame caption="Hume's WebSocket Reference Page">
 <img src="./wss-reference.png" alt="The WebSocket Reference" />
 </Frame>
-
-### WebSocket Playground
-
-<Markdown src="/snippets/pro-plan.mdx" />
-
-Users can connect to and use WebSockets from right within the API Reference (check one of Hume's WebSockets [here](https://dev.hume.ai/reference/empathic-voice-interface-evi/chat/chat)). 
-
-<Frame caption="Click 'Play' to open the WebSocket Playground">
-<img src="./websocket.png" alt="WebSocket Playground"/>
-</Frame>

fern/products/api-def/ferndef-pages/wss-reference.png

@@ -81,4 +81,4 @@ HTTP snippets automatically include:
 - If no SDK snippets exist, HTTP snippets will display automatically
 - User language preferences are saved client-side
 
-To see HTTP snippets in action, check out [Cartesia's API documentation](https://docs.cartesia.ai/api-reference/tts/bytes) for a live example of how they appear in production documentation.
+Check out [Hume's API Reference](https://dev.hume.ai/reference/voices/create) to see HTTP snippets in action.

fern/products/docs/pages/api-references/http-snippets.mdx

@@ -141,7 +141,7 @@ title: Fern's Documentation
     ```
     </CodeBlock>
 
-    To see this in practice, check out [Cartesia's Fern configuration](https://github.com/cartesia-ai/docs/tree/main/fern/apis/version-2025-04-16/definition).
+    [See an example](https://github.com/fern-api/fern/tree/3137938b70e058f3691ddef34d5c1cc29acc4b80/test-definitions/fern/apis/imdb/definition).
 
   </Accordion>
   <Accordion title="Multiple APIs">
@@ -180,6 +180,6 @@ title: Fern's Documentation
 
 ## `fern.config.json`
 
-<Markdown src="/snippets/fern-config-json-reference.mdx" />   
+<Markdown src="/snippets/fern-config-json-reference.mdx" />