Update changelogs from fern repo (#568)

Co-authored-by: mattblank11 <[email protected]>

Author: fern-support

fern/products/sdks/overview/typescript/changelog/2025-08-21.mdx

@@ -1,3 +1,20 @@
+## 2.8.4
+**`(feat):`** Add `flattenRequestParameters` to the SDK generator config.
+`flattenRequestParameters` is a boolean that controls whether to flatten request parameters.
+When `false` (default), the legacy flattening logic is used.
+When `true`, the new flattening logic is used.
+
+```yml
+# In generators.yml
+groups:
+  ts-sdk:
+    generators:
+      - name: fernapi/fern-typescript-sdk
+        config:
+          flattenRequestParameters: true
+```
+
+
 ## 2.8.3
 **`(fix):`** Set `Authorization` header for WebSocket connects when auth is available on the generated SDK client.
 This will happen regardless of whether the AsyncAPI server or channel is marked for auth.