docs: use $request./$response. prefixes in OAuth generators.yml examples

[devin-ai-integration]

Summary

The OAuth auth-schemes examples showed bare property names (access-token: access_token), but the CLI's valid-oauth rule rejects these:

OAuth configuration for endpoint auth.getToken must define a dot-delimited 'access-token' property starting with $response (e.g. $response.access-token).

A customer copied the example verbatim and hit this error. This updates every OpenAPI-side OAuth example to the accepted form ($request.<prop> under request-properties, $response.<prop> under response-properties), matching what the Fern Definition auth page already shows, and adds one sentence on the OpenAPI auth page stating the requirement.

Files: api-def/openapi/auth.mdx, sdks/snippets/oauth-params.mdx, sdks/snippets/oauth-get-token.mdx, sdks/snippets/oauth-refresh-token.mdx.

Link to Devin session: https://app.devin.ai/sessions/6cee3719d44049ffbc026381ca46ec46
Open in Devin Desktop: https://app.devin.ai/desktop/session/6cee3719d44049ffbc026381ca46ec46?variant=devin

[devin-ai-integration]

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[github-actions]

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• learn/api-definitions/openapi/authentication