review: update BatchBuilder::new docs

Co-authored-by: Mirko <48352201+Mirko-von-Leipzig@users.noreply.github.com>

crates/block-producer/src/batch_builder/mod.rs

@@ -42,7 +42,7 @@ pub struct BatchBuilder {
 impl BatchBuilder {
     /// Creates a new [`BatchBuilder`] with the given batch prover URL.
     ///
-    /// If no URL is provided, a local batch prover is used.
+    /// Defaults to [`BatchProver::Local`] is no URL is provided.
     pub fn new(batch_prover_url: Option<Url>) -> Self {
         let batch_prover = match batch_prover_url {
             Some(url) => BatchProver::new_remote(url),