Manual:$wgSiteSupportPage

Output: $wgSiteSupportPage
The title of the support page in your wiki.
Introduced in version:pre 1.1.0
Deprecated in version:1.5.0
Removed in version:1.32.0 (Gerrit change 427428; git #Iea1f8a6)
Allowed values:(string)
Default value:''

Details edit

If non-blank, this gives the title of the support page for your wiki. This can be used for whatever you like, for example to ask for donations or to provide contact details.

This has been superseded in later versions by the $wgNavigationLinks setting and the "MediaWiki:" namespace. See Manual:Interface/Sidebar for more information.