Update changelogs from fern repo (#439)

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

Author: fern-support

fern/products/sdks/overview/typescript/changelog/2025-08-13.mdx

@@ -0,0 +1,15 @@
+## 2.8.0
+**`(feat):`** Choose to use `pnpm` or `yarn` as the package manager for the generated SDK.
+Configure this in _generators.yml_ like so:
+```yml
+# In generators.yml
+groups:
+  ts-sdk:
+    generators:
+      - name: fernapi/fern-typescript-sdk
+        config:
+          packageManager: pnpm
+```
+The default is `yarn`.
+
+