Add error tracking to global nav
A new Error Tracking feature is being added to GitLab, and along with it a new page is being added to the documentation.
The idea of adding it to the nav is discussed with @axil here: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24157#note_129843039
Checklist
-
Wait until https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24275 is merged
Edited by Marcia Ramos