-'MediaWikiServices': Override services in the default MediaWikiServices instance.
-Extensions may use this to define, replace, or wrap existing services.
-However, the preferred way to define a new service is the $wgServiceWiringFiles array.
+'MediaWikiServices': Called when a global MediaWikiServices instance is
+initialized. Extensions may use this to define, replace, or wrap services.
+However, the preferred way to define a new service is
+the $wgServiceWiringFiles array.