doc: add napatech plugin upgrade notes

Issue: 7165

doc/userguide/upgrade.rst

@@ -70,6 +70,8 @@ Major changes
   <upgrade/8.0-dns-logging-changes>`.
 - PF_RING support has been moved to a plugin. See :doc:`PF_RING plugin
   <upgrade/8.0-pfring-plugin>`.
+- NAPATECH support has been moved to a plugin. See :doc:`NAPATECH plugin
+  <upgrade/8.0-napatech-plugin>`.
 
 Removals
 ~~~~~~~~

doc/userguide/upgrade/8.0-napatech-plugin.rst

@@ -0,0 +1,43 @@
+:orphan: Document only referenced from upgrade.rst
+
+NAPATECH as a Plugin
+====================
+
+Suricata 8.0 moves NAPATECH support to a dynamically loaded plugin. For
+convenience, this plugin is still bundled with Suricata, but it may be
+removed from the Suricata source tree into its own repository in a
+future release.
+
+Upgrading
+---------
+
+Suricata 8.0 continues to respect the ``--enable-napatech`` compile time
+option, as well as the ``--napatech`` command line options, and also
+the ``napatech`` section of the configuration file.
+
+.. note:: When the NAPATECH plugin is eventually removed from the
+          Suricata source tree these options may be removed and/or
+          changed as this would allow the NAPATECH plugin to have its
+          own release cycle and make changes independent of Suricata.
+
+However, the ``napatech`` plugin must be loaded before it can be
+used. If doing a fresh build of Suricata with NAPATECH support, the
+``suricata.yaml`` configuration file should be configured to load the
+plugin already, for example::
+
+  plugins:
+    - /usr/lib/suricata/napatech.so
+
+If you are upgrading, you will need to add the location of
+``napatech.so`` to the ``plugins`` section of your ``suricata.yaml``
+manually.
+
+Then your existing NAPATECH command line options and configuration
+should continue to work.
+
+Caveats
+-------
+
+Currently building the NAPATECH plugin is not compatible with the
+``--disable-shared`` configure argument.
+