datastore: fix namespace sample (#1329)

Testing, this seems to need `.Name` not `.Namespace`

Co-authored-by: Tyler Bui-Palsulich <[email protected]>

datastore/snippets/snippet_test.go

@@ -672,7 +672,7 @@ func metadataNamespaces(w io.Writer, projectID string) error {
 
 	fmt.Fprintln(w, "Namespaces:")
 	for _, k := range keys {
-		fmt.Fprintf(w, "\t%v", k.Namespace)
+		fmt.Fprintf(w, "\t%v", k.Name)
 	}
 	return nil
 }