clarify doc

Co-authored-by: Dale Seo <5466341+DaleSeo@users.noreply.github.com>

Author: jamadeo

crates/rmcp/src/transport/auth.rs

@@ -3099,7 +3099,7 @@ impl OAuthState {
     /// Use this when the client was registered with the authorization server
     /// out of band and already holds a `client_id` (and optionally a
     /// `client_secret`). If `config.scopes` is empty, scopes are selected
-    /// from the discovered authorization server metadata.
+    /// using the SDK's normal scope-selection policy.
     pub async fn start_authorization_with_preregistered_client(
         &mut self,
         mut config: OAuthClientConfig,