Add ChatClient.dispose() documentation

src/pages/docs/chat/setup.mdx

@@ -330,3 +330,40 @@ The `logLevel` sets the verbosity of logs that will be output by the SDK. The fo
 | `error` | A given operation has failed and cannot be automatically recovered. The error may threaten the continuity of operation. |
 | `silent` | No logging will be performed. |
 
+## Dispose of the client <a id="dispose"/>
+
+Use the <If lang="javascript,react">[`dispose()`](https://sdk.ably.com/builds/ably/ably-chat-js/main/typedoc/interfaces/chat-js.ChatClient.html#dispose)</If><If lang="swift">[`dispose()`](https://sdk.ably.com/builds/ably/ably-chat-swift/main/AblyChat/documentation/ablychat/chatclient/dispose%28%29)</If><If lang="kotlin,jetpack">[`dispose()`](https://sdk.ably.com/builds/ably/ably-chat-kotlin/main/dokka/chat/com.ably.chat/-chat-client/dispose.html)</If> method to release all resources associated with the chat client when you are done using it:
+
+<Code>
+```javascript
+await chatClient.dispose();
+```
+
+```react
+await chatClient.dispose();
+```
+
+```swift
+await chatClient.dispose()
+```
+
+```kotlin
+chatClient.dispose()
+```
+
+```jetpack
+chatClient.dispose()
+```
+</Code>
+
+Calling `dispose()` will:
+- Release all rooms managed by the client
+- Clean up connection listeners and timers
+- Free internal resources
+
+After calling `dispose()`, the client should not be used. Attempting to get a room after dispose has been called will throw an error. This method is idempotent, so calling it multiple times has no additional effect.
+
+<Aside data-type='note'>
+The `dispose()` method does not close the underlying Ably Realtime connection, as that connection is owned by the Pub/Sub client that was passed to the Chat client during instantiation. To close the connection, call `close()` on the Pub/Sub client directly.
+</Aside>
+