add documentation

pages/documentation/navigation_structures.md

@@ -66,6 +66,8 @@ version: 2.0
 title_url:  /events
 ```
 
+If no sidebar should be displayed, add `sidebar: false` to the frontmatter of the page or don't specify one at all.
+
 ## Top navigation and sidebar relationship
 
 Top navigation titles can be used to switch between different high level sections on the website, each having their own sidebar. As described before, sidebars are defined by the `sidebar` metadata attribute in a page, so linking in the topnav YAML towards whis page is one part of the job. To make sure that all pages within that sidebar have this topnav item on active, one has to name its sidebar file in the same way as the topnav title (spaces, hyphens and underscores get ignored).