chore: apply suggestion

Changed `add_background_task` to `add_behavior` and added extra docs.

src/control_backend/agents/perception/transcription_agent/transcription_agent.py

@@ -37,7 +37,7 @@ class TranscriptionAgent(BaseAgent):
         self.speech_recognizer.load_model()  # Warmup
 
         # Start background loop
-        await self.add_background_task(self._transcribing_loop())
+        await self.add_behavior(self._transcribing_loop())
 
         self.logger.info("Finished setting up %s", self.name)