code: public JavaFxCliBuilder setFxmlPath(String fxmlPath) {
          return setFxmlUrl(Thread.currentThread().getContextClassLoader().getResource(fxmlPath));
      }
docs: Set a path to a .fxml file containing a custom layout.
  A custom layout must have the following:
  <ul>
  <li>A {@link TextArea} with a fxml id 'cliOutput' that will be used as the terminal output.</li>
  <li>A {@link Label} with a fxml id 'workingDirectory' that will be used to display the 'workingDirectory' label.</li>
  <li>A {@link TextField} with a fxml id 'commandLine' that will be used to read and display the command line.</li>
  </ul>
  
  @param fxmlPath Path to .fxml file containing the custom layout.
  @return {@code this}, for chaining.