removed custom sum retirement notice

Author: jboback

articles/ai-services/language-service/whats-new.md

@@ -17,7 +17,6 @@ Azure AI Language is updated on an ongoing basis. To stay up-to-date with recent
 
 ## September 2024
 
-* Custom Summarization has been discontinued and is no longer available in the Studio and documentation.
 * PII detection now has container support. See our [blog post](https://techcommunity.microsoft.com/t5/ai-azure-ai-services-blog/announcing-text-pii-redaction-container-release/ba-p/4264655) for more details
 * Custom sentiment analysis (preview) will be retired on January 10th, 2025. Please transition to other custom model training services, such as custom text classification in Azure AI Language, by that date.  See more details in the [Azure Update post](https://azure.microsoft.com/en-us/updates/v2/custom-sentiment-analysis-retirement).
 * Custom text analytics for health (preview) will be retired on January 10th, 2025. Please transition to other custom model training services, such as custom named entity recognition in Azure AI Language, by that date.  See more details in the [Azure Update post](https://azure.microsoft.com/en-us/updates/v2/custom-text-analytics-for-health-retirement).