Fix note syntax in MSTEST0006 doc (#49653)

Author: Youssef1313

docs/core/testing/mstest-analyzers/mstest0006.md

@@ -27,7 +27,7 @@ dev_langs:
 | **Introduced in version**           | 3.2.0                                              |
 | **Is there a code fix**             | Yes, starting with 3.7.0                           |
 
-> [NOTE]
+> [!NOTE]
 > This analyzer is no longer relevant for MSTest 4 as the attribute was removed.
 
 ## Cause