nixos/ssh: add release notes for extraHostNames option

nixos/doc/manual/from_md/release-notes/rl-2205.section.xml

@@ -512,6 +512,15 @@
           usage in non-X11 environments, e.g. Wayland.
         </para>
       </listitem>
+      <listitem>
+        <para>
+          <link linkend="opt-programs.ssh.knownHosts">programs.ssh.knownHosts</link>
+          has gained an <literal>extraHostNames</literal> option to
+          replace <literal>hostNames</literal>.
+          <literal>hostNames</literal> is deprecated, but still
+          available for now.
+        </para>
+      </listitem>
       <listitem>
         <para>
           The <literal>services.stubby</literal> module was converted to

nixos/doc/manual/release-notes/rl-2205.section.md

@@ -180,6 +180,9 @@ In addition to numerous new and upgraded packages, this release has the followin
   `services.xserver.enable`. This allows easy usage in non-X11 environments,
   e.g. Wayland.
 
+- [programs.ssh.knownHosts](#opt-programs.ssh.knownHosts) has gained an `extraHostNames`
+  option to replace `hostNames`. `hostNames` is deprecated, but still available for now.
+
 - The `services.stubby` module was converted to a [settings-style](https://github.com/NixOS/rfcs/blob/master/rfcs/0042-config-option.md) configuration.
 
 - The option `services.duplicati.dataDir` has been added to allow changing the location of duplicati's files.