Add some comments for RDP settings.

conf/main_ipv6.conf.sample

@@ -1273,6 +1273,20 @@ remote_console_port=5900
 # - Remote Desktop Dienste
 # ======
 
+# NOTE!:
+# ======
+#
+# Do not open RDP directly to the internet
+#     Better via:
+#        SSH tunnel
+#        VPN
+#        WireGuard
+# 
+# You only need open the firewall if you open a RDP connection directly 
+# from/to the internet. this is NOT RECOMMEND
+#
+# again: if using a VPN line for yout RDP connectio no firewall settings are needed
+
 # - RDS Server local Networks
 # -
 # - Blank separated list