On Wikipedia, many Special pages show a link to a help page in the upper right-hand corner, such as can be seen here for Special:Recent changes:
One notable exception is Special:Notifications:
In T184364: Special:Notifications page does not show Help Page Link it was pointed out that there is already a help link in the settings menu, but I believe that few users will search for it there, as it is not visible by default and all (most?) other Special pages show the help link on the top right.
I therefore suggest to (re-)consider adding a clearly visible help link at the usual position for Special:Notifications.