Add note to ON_SIGHTING documentation that it's no longer necessary

data/core/macros/event-utils.cfg

@@ -50,6 +50,9 @@
 #enddef
 
 #define ON_SIGHTING ID SIGHTING_SIDE SIGHTED_FILTER ACTION_WML
+    # NOTE: As of version 1.11, this macro is unnecessary, since sighted
+    # events now work as intended.
+    #
     # This is intended to be used when a regular sighted event can't be relied
     # on (that'd be most of the time). This event triggers when a unit matching
     # SIGHTED_FILTER is first seen by a unit of side SIGHTING_SIDE. This works