Fix bad link in documentation

[vincentfretin]

npm run test:docs didn't work anymore because the referenceRegex regexp wrongly matching [Blender][blender]: Draco compression when searching for [blender]: https://www.blender.org/ type of reference. Instead of trying to modify the regexp, I just changed the doc to avoid the colon.
With that fixed, the script found a bad link caused by the renaming of webvr to webxr of the vr-headsets-and-webxr-browsers.md file.

[dmarcos]

Thanks so much!