docs: Move tip about Extension Drivers into misc section

Change-Id: Ifd458495992a0fd1b7437c315b4fe45906830cb1
diff --git a/doc/source/guides/neutron.rst b/doc/source/guides/neutron.rst
index 9d4f54a..cf48e22 100644
--- a/doc/source/guides/neutron.rst
+++ b/doc/source/guides/neutron.rst
@@ -164,11 +164,6 @@
 subnet that exists in the private RFC1918 address space - however in
 in a real setup FLOATING_RANGE would be a public IP address range.
 
-Note that extension drivers for the ML2 plugin is set by
-`Q_ML2_PLUGIN_EXT_DRIVERS`, and it includes 'port_security' by default. If you
-want to remove all the extension drivers (even 'port_security'), set
-`Q_ML2_PLUGIN_EXT_DRIVERS` to blank.
-
 Neutron Networking with Open vSwitch and Provider Networks
 ==========================================================
 
@@ -304,5 +299,11 @@
         sudo service iptables save
         sudo ufw disable
 
+Configuring Extension Drivers for the ML2 Plugin
+------------------------------------------------
 
+Extension drivers for the ML2 plugin are set with the variable
+`Q_ML2_PLUGIN_EXT_DRIVERS`, and includes the 'port_security' extension
+by default. If you want to remove all the extension drivers (even
+'port_security'), set `Q_ML2_PLUGIN_EXT_DRIVERS` to blank.