Update lmc-messages.mdx

[andrewfr]

adding information about sending audio LMC Messages. The raw audio is in wav format.

(The 01 exposes a speech-to-speech websocket at localhost:10001.

If you stream raw audio bytes to / in Streaming LMC format, you will receive its response in the same format.)

Describe the changes you have made:

Reference any relevant issues (e.g. "Fixes #000"):

Pre-Submission Checklist (optional but appreciated):

• [ ] I have included relevant documentation updates (stored in /docs)
• [x] I have read docs/CONTRIBUTING.md
• [x] I have read docs/ROADMAP.md

OS Tests (optional but appreciated):

• [ ] Tested on Windows
• [ ] Tested on MacOS
• [x] Tested on Linux