### Problem to solve With https://gitlab.com/gitlab-org/gitlab-ce/issues/14995 we are adding an option to add a custom Markdown sidebar navigation. In this first iteration, it's based on the convention to add a `_sidebar` Wiki page that overwrites the default generated table of content. We should add an option to add a custom sidebar from the UI, as well. In addition, there is the open question if besides *overwriting* the generated pages TOC, *adding* the custom sidebar, in addition, doesn't make sense as well. ### Further details (Include use cases, benefits, and/or goals) ### Proposal - When a custom sidebar is **not configured** show a link to create a custom nav which will create a `_sidebar` page - When a custom sidebar is **configured** show a link to edit the `_sidebar` page ### What does success look like, and how can we measure that? This is resolving UX debt that the custom sidebar feature isn't discoverable or easily editable. ### Links / references https://gitlab.com/gitlab-org/gitlab-ce/issues/14995