Add Voice Keyboard to the list

Voice Keyboard (https://github.com/rustemar/voice-keyboard) is a small handy speech-to-text keyboard that uses the OpenAI Whisper endpoint to transcribe speech to text. It can be used with OpenAI, Mistral and Groq. Basically anything having a compatible Whisper API.

The keyboard UI is clean and straight-forward. Right now, it can only be installed manually or with Optainium. Maybe having more popularity might change that.