Update changelogs from fern repo (#4412)

Co-authored-by: Swimburger <3382717+Swimburger@users.noreply.github.com>

Author: fern-support

fern/products/sdks/overview/csharp/changelog/2026-03-19.mdx

@@ -1,3 +1,11 @@
+## 2.38.0
+**`(feat):`** Add optional `CancellationToken` parameter to all public async WebSocket methods
+(`ConnectAsync`, `CloseAsync`, and `Send` overloads). The token is threaded through
+the internal `WebSocketClient`, `WebSocketConnection`, and down to the underlying
+`ClientWebSocket.SendAsync`/`ConnectAsync`/`CloseAsync` calls, enabling callers to
+cancel long-running WebSocket operations.
+
+
 ## 2.37.2
 **`(fix):`** Fix WebSocket binary messages being sent with `WebSocketMessageType.Text` instead of
 `WebSocketMessageType.Binary`. `RequestBinaryMessage` and `RequestBinarySegmentMessage`