vad : add a collection for VAD models on huggingface

[danbev]

This task should create a new collection for VAD models in https://huggingface.co/ggml-org.

We could then upload converted models to save users from having to do the conversion.

Added the following collection:
https://huggingface.co/collections/ggml-org/vad-6822d821781e2f27653b9ba6

I named the model silero-v5.1.2-ggml but looking at the other models this is inconsistent and should perhaps be ggml-silero-v5.1.2 instead?

[danbev]

@ggerganov Does this sound alright?

[ggerganov]

Yes, this would be useful.

[danbev]

Closed as this was added as part of #3149