style: remove incorrect comment

* src/getargs.c: here.
It's documented in getargs.h anyway.

src/getargs.c

@@ -45,7 +45,7 @@ bool no_lines_flag = false;
 bool token_table_flag = false;
 location yacc_loc = EMPTY_LOCATION_INIT;
 bool update_flag = false; /* for -u */
-bool color_debug = false; /* --style=debug. */
+bool color_debug = false;
 
 bool nondeterministic_parser = false;
 bool glr_parser = false;