Update multi-talker.md

Update one more new multi-talker voice: en-US-MultiTalker-Ava-Steffan:DragonHDLatestNeural

Author: garhe

articles/ai-services/speech-service/includes/language-support/multi-talker.md

@@ -8,8 +8,8 @@ ms.author: eur
 
 | Locale (BCP-47) | Language | Text to speech voices |
 | ----- | ----- | ----- |
-| `en-US` | English (United States) | 
-| `en-US-MultiTalker-Ava-Andrew:DragonHDLatestNeural`<sup>1</sup> (Neutral) | 
+| `en-US` | English (United States) | `en-US-MultiTalker-Ava-Andrew:DragonHDLatestNeural`<sup>1</sup> (Neutral) | 
+| `en-US` | English (United States) | `en-US-MultiTalker-Ava-Steffan:DragonHDLatestNeural`<sup>1</sup> (Neutral) | 
 
 <sup>1</sup> The neural voice is available in public preview. Voices and styles in public preview are only available in these service [regions](../../regions.md): East US, West Europe, and Southeast Asia.