improve sexp help regarding bitmasks on ship-arrival-info and ship-departure-info

Author: Goober5000

code/parse/sexp.cpp

@@ -32869,7 +32869,7 @@ sexp_help_struct Sexp_help[] = {
 		"\t1: Ship or wing name\r\n"
 		"\t2: Arrival location\r\n"
 		"\t3: Arrival anchor (optional; only required for certain locations)\r\n"
-		"\t4: Arrival path mask (optional; defaults to 0; note that this is a bitfield)\r\n"
+		"\t4: Arrival path mask (optional; this is a bitfield where the bits set to 1 correspond to the paths to use; defaults to 0 which is a special case that means all paths can be used)\r\n"
 		"\t5: Arrival distance (optional; defaults to 0)\r\n"
 		"\t6: Arrival delay (optional; defaults to 0)\r\n"
 		"\t7: Whether to show a jump effect if arriving from subspace (optional; defaults to true)\r\n"
@@ -32881,7 +32881,7 @@ sexp_help_struct Sexp_help[] = {
 		"\t1: Ship or wing name\r\n"
 		"\t2: Departure location\r\n"
 		"\t3: Departure anchor (optional; only required for certain locations)\r\n"
-		"\t4: Departure path mask (optional; defaults to 0; note that this is a bitfield)\r\n"
+		"\t4: Departure path mask (optional; this is a bitfield where the bits set to 1 correspond to the paths to use; defaults to 0 which is a special case that means all paths can be used)\r\n"
 		"\t5: Departure delay (optional; defaults to 0)\r\n"
 		"\t6: Whether to show a jump effect if departing to subspace (optional; defaults to true)\r\n"
 	},