Write realtime agent websocket blogpost

[sternakt]

Why are these changes needed?

This PR adds a blog post titled "Real-Time Voice Interactions with the WebSocket Audio Adapter" to the documentation. The post introduces the WebSocketAudioAdapter, which simplifies real-time audio interactions with the RealtimeAgent, eliminating the need for complex setups like Twilio. It provides a guide to help developers easily implement voice-enabled conversational AI applications.

Related issue number

Closes #382

Checks

• I've included any doc changes needed for https://docs.ag2.ai/. See https://docs.ag2.ai/docs/contributor-guide/documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.