Add an example illustrating loading multiple objects from a file

[kgv]

It would be great to add an example load .vox with multiple objects.

Maybe it will be useful for someone: The firsts mesh: asset_server.load("path/to/vox/name.vox"), The second mesh: asset_server.load("path/to/vox/name.vox#model1"), The third mesh: asset_server.load("path/to/vox/name.vox#model2"),