CHANGELOG.md: update release date

Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9e20a9e..3a739c1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,7 +3,7 @@
 
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 
-## [2.2.2]
+## [2.2.2] - 2019-03-28
 ### Fixed
  - Fixed wrong encryption flag in EncryptDecrypt
  - Fixing openssl engine invocation