nixos/doc: add searx changes to the relase notes

nixos/doc/manual/release-notes/rl-2103.xml

@@ -402,6 +402,18 @@ http://some.json-exporter.host:7979/probe?target=https://example.com/some/json/e
        SDK licenses if your project requires it. See the androidenv documentation for more details.
      </para>
    </listitem>
+   <listitem>
+     <para>
+      The Searx module has been updated with the ability to configure the
+      service declaratively and uWSGI integration.
+      The option <literal>services.searx.configFile</literal> has been renamed
+      to <xref linkend="opt-services.searx.settingsFile"/> for consistency with
+      the new <xref linkend="opt-services.searx.settings"/>. In addition, the
+      <literal>searx</literal> uid and gid reservations have been removed
+      since they were not necessary: the service is now running with a
+      dynamically allocated uid.
+    </para>
+   </listitem>
   </itemizedlist>
  </section>