Added a placeholder in the [Unreleased] section for the upcoming feature
to add custom warnings when a rocket is missing motors and/or aero-surface. See RocketPy-Team#285.

This enhancement adds a warning when a Rocket object has no motors,
parachutes, or AeroSurface components. It notifies the user so that
they can add missing components before running simulations. See RocketPy-Team#285

Only warn if motor or aerodynamic surfaces are missing. Never raise a warning for no parachute. See RocketPy-Team#285

- Removed redundant len() check for aerodynamic_surfaces.
- Added 'Returns: None' section to NumPy-style docstring.
- Removed redundant '[WARNING]' prefix in warnings messages.

…r: exceptions must be derived from Warning, not <class 'NoneType'>