man: add link to kernel docs for net_cls

diff --git a/man/systemd.unit.xml b/man/systemd.unit.xml
index 015deab4bb17b064a6feeb30b24fc1efca44a786..8985b6b94066f83180a1ec8a1f4292b87f8d8f1e 100644 (file)
--- a/man/systemd.unit.xml
+++ b/man/systemd.unit.xml
@@ -1055,8 +1055,11 @@
         <literal>auto</literal> (for dynamic allocation). Network traffic of
         all processes inside the unit will have the network class ID assigned
         by the kernel. Also see
-        <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
-        .</para></listitem>
+        the kernel docs for
+        <ulink url="https://www.kernel.org/doc/Documentation/cgroups/net_cls.txt">net_cls controller</ulink>
+        and
+        <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+        </para></listitem>
       </varlistentry>
     </variablelist>