add: netns usage example

netns/example.txt

@@ -0,0 +1,4 @@
+
+#sudo /opt/netns/create 18
+#/opt/netns/exec --id=18 --cmd="xterm -e screen python3 /opt/LibreLight/ASP/monitor/oszi_grid.py"
+#/opt/netns/exec --id=18 --cmd="xterm -e screen sh /opt/LibreLight/ASP/start.sh"