message: Fix typo implemeted -> implemented
diff: @@ -71,7 +71,7 @@ pub trait Storage: ReadonlyStorage {
  fn remove(&mut self, key: &[u8]);
  }
  -/// Api are callbacks to system functions implemeted outside of the wasm modules.
  +/// Api are callbacks to system functions implemented outside of the wasm modules.
  /// Currently it just supports address conversion but we could add eg. crypto functions here.
  ///
  /// This is a trait to allow mocks in the test code. Its members have a read-only
  