message: Update README.md
  Remove mention of plugins for older versions of three.js/Babylon.js since they were removed from the repository.
diff: @@ -22,7 +22,7 @@ gltfpack substantially changes the glTF data by optimizing the meshes for vertex
  By default gltfpack outputs regular `.glb`/`.gltf` files that have been optimized for GPU consumption using various cache optimizers and quantization. These files can be loaded by GLTF loaders that support `KHR_mesh_quantization` extension such as [three.js](https://threejs.org/) (r111+) and [Babylon.js](https://www.babylonjs.com/) (4.1+).
  -When using `-c` option, gltfpack outputs compressed `.glb`/`.gltf` files that use meshoptimizer codecs to reduce the download size further. Loading these files requires extending GLTF loaders with support for `EXT_meshopt_compression` extension; three.js supports it in r122+ (requires calling `GLTFLoader.setMeshoptDecoder`), Babylon.js supports it in 5.0+ without further setup. Plugins for older versions of [three.js](https://github.com/zeux/meshoptimizer/blob/master/js/THREE.EXT_meshopt_compression.js) and [Babylon.js](https://github.com/zeux/meshoptimizer/blob/master/js/babylon.EXT_meshopt_compression.js) are provided as well.
  +When using `-c` option, gltfpack outputs compressed `.glb`/`.gltf` files that use meshoptimizer codecs to reduce the download size further. Loading these files requires extending GLTF loaders with support for `EXT_meshopt_compression` extension; three.js supports it in r122+ (requires calling `GLTFLoader.setMeshoptDecoder`), Babylon.js supports it in 5.0+ without further setup.
  For better compression, you can use `-cc` option which applies additional compression; additionally make sure that your content delivery method is configured to use deflate (gzip) - meshoptimizer codecs are designed to produce output that can be compressed further with general purpose compressors.
  