Update README.md

Remove outdated information about `-tb` option.

Fixes #272.

gltf/README.md

@@ -26,7 +26,7 @@ When using `-c` option, gltfpack outputs compressed `.glb`/`.gltf` files that us
 
 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.
 
-gltfpack can also compress textures using Basis Universal format, either storing .basis images directly (`-tb` flag, supported by three.js) or using KTX2 container (`-tc` flag, requires support for `KHR_texture_basisu`). Compression is performed using `basisu` executable that must be available in `PATH`; alternatively the path to the executable can be specified via `BASISU_PATH` environment variable. Textures can also be embedded into `.bin`/`.glb` output using `-te` flag.
+gltfpack can also compress textures using Basis Universal format stored in a KTX2 container (`-tc` flag, requires support for `KHR_texture_basisu`). Compression is performed using `basisu` or `toktx` executable that must be available in `PATH`; alternatively the path to the executable can be specified via `BASISU_PATH`/`TOKTX_PATH` environment variable accordingly. Textures can also be embedded into `.bin`/`.glb` output using `-te` flag.
 
 ## Decompression