Update changelogs from fern repo (#5125)

Co-authored-by: dsinghvi <10870189+dsinghvi@users.noreply.github.com>

Author: fern-support

fern/products/cli-api-reference/cli-changelog/2026-04-23.mdx

@@ -1,3 +1,9 @@
+## 4.91.1
+**`(fix):`** Update CLI v2 authentication error messages to reference `fern auth login` instead of `fern login`.
+This covers SDK generation permission errors, docs publish auth failures, and missing-token hints
+produced by CLI v2 code paths. The legacy `fern login` wording is preserved for the v1 CLI.
+
+
 ## 4.91.0
 **`(internal):`** Remove the abandoned `@fern-api/docs-parsers` dependency from `@fern-api/docs-resolver` and drop
 the hidden `fern fdr <path> --v2` code path that was the only remaining consumer. The upstream