Docs: Add LightProbe to the object list in ObjectLoader

[cloud9c]

Added LightProbe to the list of parse-able objects in the ObjectLoader documentation

[mrdoob]

Thanks!

[Mugen87]

@mrdoob Listings like in ObjectLoader.parseObject() can easily get out of date and are thus hard to maintain. Next to LightProbe, the classes RectAreaLight, SkinnedMesh and InstancedMesh are also missing.

How about removing it? I mean the listing comes from a time where ObjectLoader did only partly support 3D objects. Right now, all classes from src/objects and all non-experimental lights are supported.

[mrdoob]

Sounds good to me 👍