Adding clearer comment for batch auth on first request

Author: EddieHouston

src/raw_client.rs

@@ -967,7 +967,7 @@ impl<T: Read + Write> ElectrumApi for RawClient<T> {
                 params.to_vec(),
             );
 
-            // Apply authorization token only to the first request in batch
+            // Servers expect auth token only in the first request in batched requests
             if index == 0 {
                 if let Some(provider) = &self.auth_provider {
                     req.authorization = provider();