message: update plugin example to pass empty vec for mapped_dir arg
diff: @@ -17,7 +17,7 @@ fn main() {
  ));
  // WASI imports
  - let mut base_imports = generate_import_object(vec![], vec![], vec![]);
  + let mut base_imports = generate_import_object(vec![], vec![], vec![], vec![]);
  // env is the default namespace for extern functions
  let custom_imports = imports! {
  "env" => {
  