Docs:: Add documentation for ClippingGroup()

[aardgoose]

Add a first draft documentation page for ClippingGroup.

Should ClippingGroup (and BundleGroup) be moved to src/objects with other Object3D subclasses?

Can some markup/labelling be applied to indicate that a feature is WebGPURenderer only.?

[Mugen87]

Should ClippingGroup (and BundleGroup) be moved to src/objects with other Object3D subclasses?

Yes, that sounds good to me.

Can some markup/labelling be applied to indicate that a feature is WebGPURenderer only.?

Until we find a solution, you can use a simple note under the description. We've used this approach for WebGL 2 only features as well. Maybe:

Note: ClippingGroup is only supported with WebGPURenderer.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	692.22 171.45	692.22 171.45	+0 B +0 B
WebGPU	825.22 222.85	825.22 222.84	+0 B -4 B
WebGPU Nodes	824.33 222.64	824.5 222.69	+171 B +47 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	464.58 112.26	464.58 112.26	+0 B +0 B
WebGPU	545.43 147.71	545.43 147.71	+0 B +0 B
WebGPU Nodes	501.37 137.44	501.37 137.44	+0 B +0 B