Clean up comments in MistralTTSService

src/pipecat/services/mistral/tts.py

@@ -71,12 +71,10 @@ class MistralTTSService(TTSService):
         """Initialize Mistral TTS service.
 
         Args:
-            api_key: Mistral API key for authentication. If None, uses
-                MISTRAL_API_KEY environment variable.
+            api_key: Mistral API key for authentication.
             sample_rate: Output audio sample rate in Hz. Audio is resampled from
                 Mistral's native 24kHz when a different rate is requested.
-            settings: Runtime-updatable settings. When provided alongside deprecated
-                parameters, ``settings`` values take precedence.
+            settings: Runtime-updatable settings.
             **kwargs: Additional keyword arguments passed to TTSService.
         """
         # Initialize default_settings with hardcoded defaults