add a note to "unknown parameter" error about -k autodetect failure.

common/param.c

@@ -124,7 +124,7 @@ static struct command_result *parse_by_name(struct command *cmd,
 		if (!p) {
 			if (!allow_extra) {
 				return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
-						    "unknown parameter: %.*s",
+						    "unknown parameter: %.*s, this may be caused by a failure to autodetect key=value-style parameters. Please try using the -k flag and explicit key=value pairs of parameters.",
 						    t->end - t->start,
 						    buffer + t->start);
 			}