I will add a link to the project README. In Jenkins plug-ins, GitHub is used only for code & pull requests. Issues are always in issues.jenkins-ci.org
When logging an issue for a plug-in in Jenkins, remember to pick the plug-in you are reporting the issue against as "component" (search in the new issue screen for that field).
I'm the default assignee of the active-choices-plugin. If you have a fix for the issue, feel free to include a link to the PR (although I also receive notifications). Issues with PR's are normally easier/quicker to fix & release :)