Update changelogs from fern repo (#537)

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

Author: fern-support

fern/products/sdks/overview/go/changelog/2025-08-20.mdx

@@ -1,3 +1,7 @@
+## 1.6.0
+**`(feat):`** Add support for specifying a custom subdirectory to generate into.
+
+
 ## 1.5.8
 **`(fix):`** Fix named string literals in undiscriminated unions.