The "sitemap-extra" setting:
The sitemap-extra setting defines extra links to appear on the /sitemap web page as sub-items of the "Home Page" entry before the "Documentation Search" entry (if any). For skins that use the /sitemap page to construct a hamburger menu dropdown, new entries added here will appear on the hamburger menu.
This setting should be a TCL list divided into triples. Each triple defines a new entry:
The first term is the display name of the /sitemap entry
The second term is a hyperlink to take when a user clicks on the entry. Hyperlinks that start with "/" are relative to the repository root.
The third term is an argument to the TH1 "capexpr" command. If capexpr evaluates to true, then the entry is shown. If not, the entry is omitted. "*" is always true.
The default value is blank, meaning no added entries.