KHR_mesh_quantization: Clarify dequantization transform

It took me a few reads of the KHR_mesh_quantization extension to wrap my head around how the quantization is defined for a mesh. If my understanding is correct, the external encoder will insert a dequantization transform to encode a scale and bias; in effect this transformation would map POSITION data into a unit (ish) cube.

If this is correct, I'd recommend this extension illustrates this upfront, with a glTF snippet or diagram showing the dequantization transform node. Here's a quick mockup of something in powerpoint, with made up numbers, that I personally would have found helpful.

Start with the KHR_mesh_quantization extension text and the linked mockup image to verify how the dequantization transform is described. Done means the extension explains the transform upfront and includes a glTF snippet or diagram that makes the scale-and-bias mapping clear.

Written by the indexing model from the issue text.