docs: note the Cohere/Voyage model check needs non-empty docs

Author: TheGreatAxios

README.md

@@ -67,7 +67,7 @@ Providers reply with positions into the request array, so each score maps back t
 
 ## Errors
 
-Failures throw `RerankRequestError` (`extends Error`), carrying the classified `InferenceError` from `@intx/inference` as `reason` and the request `url`. That covers transport failures, HTTP errors, and replies in the wrong shape; retryable errors are retried first under the `retryPolicy` option, which defaults to `createDefaultRetryPolicy()`. An invalid config, including a missing `model` for Cohere or Voyage, throws arktype's `TraversalError` before any request is sent; an `apiStyle` the registry does not know throws a plain `Error` naming it.
+Failures throw `RerankRequestError` (`extends Error`), carrying the classified `InferenceError` from `@intx/inference` as `reason` and the request `url`. That covers transport failures, HTTP errors, and replies in the wrong shape; retryable errors are retried first under the `retryPolicy` option, which defaults to `createDefaultRetryPolicy()`. An invalid config throws arktype's `TraversalError` before any request is sent, as does a missing `model` for Cohere or Voyage once `docs` is non-empty (an empty `docs` returns `[]` without building a request); an `apiStyle` the registry does not know throws a plain `Error` naming it.
 
 Fallback is left to the caller: catch the error and keep your own ordering if a reranker outage should not fail search.