GitLab

GitLab is an open source code repository and collaborative software development platform for large DevOps and DevSecOps projects. GitLab offers a location for online code storage and capabilities for issue tracking and CI/CD. The repository enables hosting different development chains and versions, and allows users to inspect previous code and roll back to it in the event of unforeseen problems.

More info about the project can be found here, https://about.gitlab.com/

Manual

New GitLab user? Here is the GitLab handbook that will help you learn more about the mission and how the company is run: https://about.gitlab.com/handbook/. Also, this might be handy to check before opening a support ticket for your instance.