Manual:$wgNamespacesToBeSearchedHelp

Details
Namespaces to be searched when user clicks the "Help" tab on Special:Search with the new search interface ( ).

Same format as  .

To have a working search header you have to take care of a few things:


 * Namespaces you set in   should not be set in  .


 * Otherwise it will display the NS Selector under "Content pages"

So e.g. not Help before Project.
 * The order of the set namespaces in the array is important! Be sure to set them in the order of the ns>Special:MyLanguage/Manual:Namespace#Built-in_namespaces|namespace number.


 * Otherwise clicking "Help and Project pages" takes you to "Advanced"