Add missing release date

Author: Nicola Moretto

versioned_docs/version-2.2.x/p4samd/release-notes/v2.1.md

@@ -4,6 +4,8 @@ title: Version 2.1 Release Notes
 sidebar_label: v2.1
 ---
 
+_May 28th, 2025_
+
 ## AI-powered assessment of Design Input
 
 P4SaMD introduces AI-powered features to enhance quality and accelerate the development process: the first features aim to to improve the quality of design inputs and testing: