Update for better naming and vehicle classes in vMenu

[joe-p]

vehicles.meta changes

• I updated the vehicles.meta files and made gameName match the modelName to get proper naming in vMenu as per the vMenu documentation.
• Added example_vmenu_addons.json as an example addons.json for vMenu.
• Corrected the vehicle class for vehicles that were obviously in the wrong class. There is some blurred lines when it comes to sports vs sedan/coupe or sports vs sports classic, so I left those vehicles as they were unless it was obviously wrong.

README changes

• Added ensure PLOKS_CARS example to replace ploks-cars.cfg

Other changes

• removed ploks-cars.cfg since it only contained a single line that can be embedded into the README

[PLOKMJNB]

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