update documentation

* main.go: Here.

main.go

@@ -542,7 +542,7 @@ var (
 	formulae       = flag.String("formulae", "", "Formulae file")
 	maxdepth       = flag.Int("maxdepth", 10, "fix the maximum depth of recursion for a recursive file")
 	output         = flag.String("o", "output", "output `directory`")
-	rers           = flag.Bool("rers", false, "support for RERS challenge: instruction \"__RERS += __RERS__ + 1\" will be\nreplaced to simulate environment, i.e. this instruction will produce as many\nsuccessors as values in parameters.\n./go2pins -rers \"val1;val2;val3\"")
+	rers           = flag.Bool("rers", false, "support for RERS challenge: instruction \"__RERS += __RERS__ + 1\" will be\nreplaced to simulate environment, i.e. this instruction will produce as many\nsuccessors as specified by the environment (inputs field).\"")
 	version        = flag.Bool("version", false, "The current version of Go2Pins")
 )