add secure only mode example in config

config.py

@@ -8,3 +8,7 @@ USERS = {
 
 # Tag for advertising, obtainable from @MTProxybot
 # AD_TAG = "3c09c680b76ee91a4c25ad51f742267d"
+
+# Uncommenting this do make a proxy harder to detect
+# But it can be incompatible with old clients
+# SECURE_ONLY = True