'SearchableNamespaces': An option to modify which namespaces are searchable.
&$arr : Array of namespaces ($nsId => $name) which will be used.
+'SecondaryDataUpdates': Allows modification of the list of DataUpdates to
+perform when page content is modified. Currently called by
+AbstractContent::getSecondaryDataUpdates.
+$title: Title of the page that is being edited.
+$oldContent: Content object representing the page's content before the edit.
+$recursive: bool indicating whether DataUpdates should trigger recursive
+ updates (relevant mostly for LinksUpdate).
+$parserOutput: ParserOutput representing the rendered version of the page
+ after the edit.
+&$updates: a list of DataUpdate objects, to be modified or replaced by
+ the hook handler.
+
'SelfLinkBegin': Called before a link to the current article is displayed to
allow the display of the link to be customized.
$nt: the Title object