Update region-support.md - add Germany West Central

Author: ylxiongwork

articles/ai-services/language-service/summarization/region-support.md

@@ -29,6 +29,7 @@ Some summarization features are only available in limited regions. More regions
 |East US           |✅                           |✅                                        |
 |East US 2         |✅                           |✅                                        |
 |France Central    |✅                           |✅                                        |
+|Germany West Central  |✅                           |✅                                        |
 |Italy North       |✅                           |✅                                        |
 |Japan East        |✅                           |✅                                        |
 |North Central US  |✅                           |✅                                        |