Fix grammar in comment

Author: Emil Iggland

src/backend/commands/publicationcmds.c

@@ -525,7 +525,7 @@ OpenTableList(List *tables)
 		myrelid = RelationGetRelid(rel);
 		/*
 		 * filter out duplicates when user specifies "foo, foo"
-		 * Note that this algorithm is know to not be very effective (O(N^2))
+		 * Note that this algorithm is known to not be very efficient (O(N^2))
 		 * but given that it only works on list of tables given to us by user
 		 * it's deemed acceptable.
 		 */