add help for nowidelut and abc9 options

techlibs/gowin/synth_gowin.cc

diff --git a/techlibs/gowin/synth_gowin.cc b/techlibs/gowin/synth_gowin.cc
index a70ff93..bb6d44e 100644
--- a/techlibs/gowin/synth_gowin.cc
+++ b/techlibs/gowin/synth_gowin.cc
@@ -64,6 +64,12 @@
 		log("    -retime\n");
 		log("        run 'abc' with -dff option\n");
 		log("\n");
+		log("    -nowidelut\n");
+		log("        do not use muxes to implement LUTs larger than LUT4s\n");
+		log("\n");
+		log("    -abc9\n");
+		log("        use new ABC9 flow (EXPERIMENTAL)\n");
+		log("\n");
 		log("\n");
 		log("The following commands are executed by this synthesis command:\n");
 		help_script();
@@ -173,7 +179,7 @@
 		{
 			run("synth -run coarse");
 		}
-		
+
 		if (!nobram && check_label("bram", "(skip if -nobram)"))
 		{
 			run("memory_bram -rules +/gowin/bram.txt");