Many WMF wikis display a Help:Searching link on the Special:Search page by adding the message key 'search-summary' which SpecialPage.php outputs in outputHeader(). But it doesn't render it with the addHelpLink() standard '(?)' help UX used on most other special pages, e.g. https://www.mediawiki.org/wiki/Special:LinkSearch.
A fix is to add the standard addHelpLink() code to SpecialSearch.php using a different message key such as 'Help:Search', then over time wikis can remove 'search-summary' in favor of this.