We offer a wiki https://docs.gitlab.com/ce/user/project/wiki/index.html which has less features than Confluence but does work with markdown and is stored in git.

Many of our users switched from a wiki to a static website so they can use merge/pull requests to handle changes. GitLab Pages https://about.gitlab.com/features/pages/ has support for more than 30 static site generations.

GitLab has issues https://docs.gitlab.com/ee/user/project/issues/ and an issue board https://about.gitlab.com/features/issueboard/ By default you can do Kanban and time tracking. Next month we'll come out with relations between issues.