Explain a user should call setSessionCookieTimeout when changing visit length

config/global.ini.php

@@ -614,7 +614,9 @@ cookie_path =
 record_statistics = 1
 
 ; length of a visit in seconds. If a visitor comes back on the website visit_standard_length seconds
-; after his last page view, it will be recorded as a new visit
+; after his last page view, it will be recorded as a new visit. In case you are using the Piwik JavaScript tracker to 
+; calculate the visit count correctly, make sure to call the method "setSessionCookieTimeout" eg 
+; `_paq.push(['setSessionCookieTimeout', timeoutInSeconds=1800000])`
 visit_standard_length = 1800
 
 ; The window to look back for a previous visit by this current visitor. Defaults to visit_standard_length.