Docs for config change log
What does this MR do and why?
This MR updates the documentation for configuring a GitLab Dedicated instance. It adds a section under Configuration changes in Switchboard on viewing the configuration change log, which allows users to track changes made to their instance.
Relates to: https://gitlab.com/groups/gitlab-com/gl-infra/gitlab-dedicated/-/epics/337+
The merge request also includes minor style updates to replace 'log in' with 'sign in', per our documentation style guide.
Edited by Lysanne Pinto