Added v3.1.0 into changelog

Author: vyskocilpavel

CHANGELOG.md

@@ -2,6 +2,8 @@
 All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
+
+## [v3.1.0]
 #### Added
 - Added configuration file for ESLint
 - Module now supports running statistics as IDP/SP
@@ -110,6 +112,7 @@ All notable changes to this project will be documented in this file.
 - Changelog
 
 [Unreleased]: https://github.com/CESNET/proxystatistics-simplesamlphp-module/tree/master
+[v3.1.0]: https://github.com/CESNET/proxystatistics-simplesamlphp-module/tree/v3.1.0
 [v3.0.0]: https://github.com/CESNET/proxystatistics-simplesamlphp-module/tree/v3.0.0
 [v2.1.0]: https://github.com/CESNET/proxystatistics-simplesamlphp-module/tree/v2.1.0
 [v2.0.0]: https://github.com/CESNET/proxystatistics-simplesamlphp-module/tree/v2.0.0