Added v3.1.0 into changelog

Author: Pavel Vyskočil

CHANGELOG.md

@@ -2,6 +2,8 @@
 All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
+
+## [v3.1.0]
 #### Added
 - PerunAttribute process filter - Added support for numeric attributes
 
@@ -129,6 +131,7 @@ when storing one Perun attribute to more SAML attribute
 ## [v1.0.0]
 
 [Unreleased]: https://github.com/CESNET/perun-simplesamlphp-module/tree/master
+[v3.1.0]: https://github.com/CESNET/perun-simplesamlphp-module/tree/v3.1.0
 [v3.0.4]: https://github.com/CESNET/perun-simplesamlphp-module/tree/v3.0.4
 [v3.0.3]: https://github.com/CESNET/perun-simplesamlphp-module/tree/v3.0.3
 [v3.0.2]: https://github.com/CESNET/perun-simplesamlphp-module/tree/v3.0.2