fix: grammar error

cmd/crudgen/main.go

@@ -27,7 +27,7 @@ func ImplementServices(mainPkgDir string, reimplement bool) {
 func main() {
 	log.SetFlags(0)
 	projectPath := flag.String("p", ".", "project path")
-	reimplement := flag.Bool("f", false, "pass -f to allow tool to overwrite exist functions and service structure")
+	reimplement := flag.Bool("f", false, "pass -f to allow tool to overwrite existing functions and service structure")
 	flag.Parse()
 	ImplementServices(*projectPath, *reimplement)
 }