Update pronunciation-assessment.md

Author: sally-baolian

articles/ai-services/speech-service/includes/language-support/pronunciation-assessment.md

@@ -11,6 +11,7 @@ ms.author: eur
 |Arabic (Saudi Arabia)|`ar-SA` |
 |Chinese (Cantonese, Traditional)|`zh-HK`<sup>1</sup>|
 |Chinese (Mandarin, Simplified)|`zh-CN`|
+|Dutch (Netherlands)|`nl-NL`<sup>1</sup>|
 |English (Australia)|`en-AU`|
 |English (Canada)|`en-CA` |
 |English (India)|`en-IN` |