upd doc

README.md

@@ -89,6 +89,8 @@ Options:
     	hex-encoded pre-shared key. Can be generated with genpsk subcommand
   -skip-hello-verify
     	(server only) skip hello verify request. Useful to workaround DPI
+  -stale-mode value
+    	which stale side of connection makes whole session stale (both, either, left, right) (default either)
   -timeout duration
     	network operation timeout (default 10s)
 ```

cmd/dtlspipe/main.go

@@ -77,7 +77,7 @@ var (
 func init() {
 	flag.Var(&ciphersuites, "ciphers", "colon-separated list of ciphers to use")
 	flag.Var(&curves, "curves", "colon-separated list of curves to use")
-	flag.Var(&staleMode, "stale-mode", "which stale side of connection makes whole session stale")
+	flag.Var(&staleMode, "stale-mode", "which stale side of connection makes whole session stale (both, either, left, right)")
 }
 
 func usage() {