Copy docs into Zeek repo directly

This is based on commit 99e6942efec5feff50523f6b2a1f5868f19ab638 from the
zeek-docs repo.

doc/frameworks/netcontrol-1-drop-with-debug.zeek

@@ -0,0 +1,10 @@
+event NetControl::init()
+	{
+	local debug_plugin = NetControl::create_debug(T);
+	NetControl::activate(debug_plugin, 0);
+	}
+
+event connection_established(c: connection)
+	{
+	NetControl::drop_connection(c$id, 20 secs);
+	}