Update overview.md

Author: jinruishao

articles/ai-services/content-safety/overview.md

@@ -135,7 +135,7 @@ See the following list for the input requirements for each feature.
   - Maximum length for grounding sources: 55,000 characters (per API call).
   - Maximum text and query length: 7,500 characters.
 - **Protected material detection APIs**: 
-  - Default maximum length: 1K characters.
+  - Default maximum length: 10K characters.
   - Default minimum length: 110 characters (for scanning LLM completions, not user prompts).
 - **Custom categories (standard) API (preview)**:
   - Maximum inference input length: 1K characters.