Document "version redirection disabled" message and fern api update "Mi…

[fern-api]

Added <llms-only> documentation for two undocumented CLI behaviors that were generating Ask AI gaps. In the fern docs dev accordion (docs-commands.mdx), added a note explaining that "Version redirection is disabled, so it was not upgraded" is informational — the command still runs on the locally pinned version from fern.config.json and can be safely ignored during local development. The same entry was added to the Common errors <llms-only> section in preview-changes-locally.mdx. In the fern api update accordion (general-commands.mdx), added a note explaining that the target OpenAPI file must already exist on disk before the command runs, with a touch example showing how to create the placeholder first.

[github-actions]

🚫 [vale] <Microsoft.Contractions> _{reported by reviewdog 🐶}
Use 'doesn't' instead of 'does not'.

Suggested change

	`fern api update` downloads the remote spec and overwrites the local file referenced by the `openapi:` path in `generators.yml`. The target file must already exist on disk before the command runs — the command updates an existing file in place and does not create new files.
	`fern api update` downloads the remote spec and overwrites the local file referenced by the `openapi:` path in `generators.yml`. The target file must already exist on disk before the command runs — the command updates an existing file in place and doesn't create new files.

[github-actions]

🚫 [vale] <Microsoft.Contractions> _{reported by reviewdog 🐶}
Use 'wasn't' instead of 'was not'.

Suggested change

	#### "Version redirection is disabled, so it was not upgraded"
	#### "Version redirection is disabled, so it wasn't upgraded"

[github-actions]

🚫 [vale] <Microsoft.Contractions> _{reported by reviewdog 🐶}
Use 'can't' instead of 'cannot'.

Suggested change

	This message is informational. It appears when the CLI cannot redirect to a different version — for example, because the organization's version policy cannot be reached, or because the CLI is running in an environment where version redirection is suppressed. The command still runs using the locally pinned version from `fern.config.json`. It is safe to ignore during local development.
	This message is informational. It appears when the CLI can't redirect to a different version — for example, because the organization's version policy cannot be reached, or because the CLI is running in an environment where version redirection is suppressed. The command still runs using the locally pinned version from `fern.config.json`. It is safe to ignore during local development.

[github-actions]

🚫 [vale] <Microsoft.Contractions> _{reported by reviewdog 🐶}
Use 'can't' instead of 'cannot'.

Suggested change

	This message is informational. It appears when the CLI cannot redirect to a different version — for example, because the organization's version policy cannot be reached, or because the CLI is running in an environment where version redirection is suppressed. The command still runs using the locally pinned version from `fern.config.json`. It is safe to ignore during local development.
	This message is informational. It appears when the CLI cannot redirect to a different version — for example, because the organization's version policy can't be reached, or because the CLI is running in an environment where version redirection is suppressed. The command still runs using the locally pinned version from `fern.config.json`. It is safe to ignore during local development.

[github-actions]

🚫 [vale] <Microsoft.Contractions> _{reported by reviewdog 🐶}
Use 'it's' instead of 'It is'.

Suggested change

	This message is informational. It appears when the CLI cannot redirect to a different version — for example, because the organization's version policy cannot be reached, or because the CLI is running in an environment where version redirection is suppressed. The command still runs using the locally pinned version from `fern.config.json`. It is safe to ignore during local development.
	This message is informational. It appears when the CLI cannot redirect to a different version — for example, because the organization's version policy cannot be reached, or because the CLI is running in an environment where version redirection is suppressed. The command still runs using the locally pinned version from `fern.config.json`. it's safe to ignore during local development.

[github-actions]

🌿 Preview your docs: https://fern-preview-2026-09-21-fern-ai-d8be69-c84a544d.docs.buildwithfern.com/learn

Here are the markdown pages you've updated:

• learn/cli-api-reference/cli-reference/docs-commands
• learn/cli-api-reference/cli-reference/general-commands
• learn/docs/preview-publish/preview-changes