Update README.md

Author: larsl2005

README.md

@@ -9,3 +9,4 @@ Put "GTAG_NotificationLib.dll" in the "plugins" folder in the BepInEx folder.
 Add "GTAG_NotificationLib.dll" as an assembly reference to your project.
 Put "using GTAG_NotificationLib;" at the top of the project.
 To send a notification, use "NotifiLib.SendNotification("Whatever you want here");"
+To check the previously sent notification. use "NotifiLib.PreviousNotifi" (to prevent sending the same notification twice for example);