Note: The notifications will now use the icons listed in https://commons.wikimedia.org/wiki/Category:Notifications_Wikimedia_site_icons
We now have the welcome and user-rights notifications defaulting to the generic notification icon, but we want to override these on wikipedia projects.
Within echo each notification has a name of the icon that should be displayed. $wgEchoNotificationIcons is a map from these names to the data necesary to load them. Both the welcome and user-rights notifications use an icon named 'site'.
CommonSettings.php already has:
$wgEchoNotificationIcons['site']['url'] = $wmgEchoSiteNotificationIconUrl;
InitializeSettings.php should be adjusted to something like:
'wmgEchoSiteNotificationUrl' => array(
'default' => false,
'wikipedia' => 'https://commons.wikipedia.org/....',
'wikibooks' => 'https://....',