Add vehicle_menu to the Bridge Menu options

[PenguScript]

Needed additional information for this example, spent 30 minutes lost because I didn't know it required an ID.

Pull Request Checklist

• [ n/a ] PR is targeting the dev branch
• I have pulled the latest changes from dev and resolved any merge conflicts
• My code follows the project’s style guidelines
• I have tested my changes and ensured they work as expected
• Relevant documentation/comments have been added or updated
• Any dependent changes have been merged

Description

This PR makes a small update to the menu example in the documentation, specifying an explicit menu ID for clarity and best practices. Also, if using ox_lib it is a requirement to include an ID which isn't specified in the example.

Testing Steps

This pull request makes a minor update to the menu example in the documentation by adding an explicit id field to the menu definition. This helps clarify how to specify a unique identifier for a menu.

Additional Notes

• Added an id property ("vehicle_menu") to the menu configuration example in menu.md to demonstrate how to set a unique menu identifier.