Add checklist items to activity log.

Thanks to GhassenRjab ! Closes #1025

CHANGELOG.md

@@ -4,7 +4,8 @@ This release adds the following new features:
 
 * [More screenshots at Features page](https://github.com/wekan/wekan/wiki/Features);
 * [Export and import boards in Sandstorm](https://github.com/wekan/wekan/pull/1144);
-* [GitHub Issue template](https://github.com/wekan/wekan/pull/1146).
+* [GitHub Issue template](https://github.com/wekan/wekan/pull/1146);
+* [Add checklist items to activity log](https://github.com/wekan/wekan/pull/1148).
 
 and fixes the following bugs: