improve a minor info message

vlib/compiler/main.v

@@ -522,7 +522,7 @@ pub fn (v &V) v_files_from_dir(dir string) []string {
 	if !os.file_exists(dir) {
 		if dir == 'compiler' && os.dir_exists('vlib') {
 			println('looks like you are trying to build V with an old command')
-			println('use `v v.v` instead of `v -o v compiler`')
+			println('use `v -o v v.v` instead of `v -o v compiler`')
 		}	
 		verror("$dir doesn't exist")
 	} else if !os.dir_exists(dir) {