chore: add reference to output (#2131)

Author: koppor

src/main/java/dev/jbang/source/resolvers/RemoteResourceResolver.java

@@ -46,7 +46,7 @@ public ResourceRef resolve(String resource, boolean trusted) {
 						try {
 							return alwaysTrust || trusted ? fetchFromURL(ref) : fetchScriptFromUntrustedURL(ref);
 						} catch (IOException | URISyntaxException e) {
-							throw new ResourceNotFoundException(resource, "Could not download", e);
+							throw new ResourceNotFoundException(resource, "Could not download " + ref, e);
 						}
 					});
 		}