Updated 2.6.0 release notes.

Author: Ruhanga

README.md

@@ -188,6 +188,7 @@ See the [documentation on Initializer's logging properties](readme/rtprops.md#lo
 ## Releases notes
 
 #### Version 2.6.0
+* Added support for Cohort Attribute types
 
 #### Version 2.5.2
 * Updated versions of Validator's metadatamapping to 1.6.0 and metadatasharing to 1.9.0.