doc: mention the new format expected by the new vim updater

e.g., from simple strings to csv

nixos/doc/manual/from_md/release-notes/rl-1803.section.xml

@@ -866,6 +866,14 @@
           package.
         </para>
       </listitem>
+      <listitem>
+        <para>
+          The vim/kakoune plugin updater now reads from a CSV file:
+          check
+          <literal>pkgs/applications/editors/vim/plugins/vim-plugin-names</literal>
+          out to see the new format
+        </para>
+      </listitem>
     </itemizedlist>
   </section>
 </section>

nixos/doc/manual/release-notes/rl-1803.section.md

@@ -282,3 +282,5 @@ When upgrading from a previous release, please be aware of the following incompa
 - The NixOS test driver supports user services declared by `systemd.user.services`. The methods `waitForUnit`, `getUnitInfo`, `startJob` and `stopJob` provide an optional `$user` argument for that purpose.
 
 - Enabling bash completion on NixOS, `programs.bash.enableCompletion`, will now also enable completion for the Nix command line tools by installing the [nix-bash-completions](https://github.com/hedning/nix-bash-completions) package.
+
+- The vim/kakoune plugin updater now reads from a CSV file: check `pkgs/applications/editors/vim/plugins/vim-plugin-names` out to see the new format