Point users to xAI's custom voices feature — clone your voice in the
console, paste the voice_id into tts.xai.voice_id. No code changes
needed; the existing TTS pipeline already handles arbitrary voice IDs.
- config.py: link to xAI custom voices docs in voice_id comment
- setup.py: prompt accepts custom voice IDs during xAI TTS setup
- tts.md: short section linking to xAI console and docs