impl pr feedback

Author: MannDP

kernel/src/transaction/mod.rs

@@ -303,7 +303,7 @@ impl Transaction {
         for domain_metadata in domain_metadatas {
             if domain_metadata.is_internal() {
                 return Err(Error::Generic(
-                    "Users cannot modify system controlled metadata domains".to_string(),
+                    "Cannot modify domains that start with 'delta.' as those are system controlled".to_string(),
                 ));
             }
             if !domains.insert(domain_metadata.domain()) {

kernel/tests/write.rs

@@ -1291,7 +1291,7 @@ async fn test_set_domain_metadata_errors() -> Result<(), Box<dyn std::error::Err
         .commit(&engine);
     assert_result_error_with_message(
         res,
-        "Users cannot modify system controlled metadata domains",
+        "Cannot modify domains that start with 'delta.' as those are system controlled",
     );
 
     // Duplicate domain rejection