bird1: drop package + modules

reason: no longer maintained upstream.

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

@@ -546,6 +546,14 @@
           <literal>tilp2</literal> was removed together with its module
         </para>
       </listitem>
+      <listitem>
+        <para>
+          <literal>bird1</literal> and its modules
+          <literal>services.bird</literal> as well as
+          <literal>services.bird6</literal> have been removed. Upgrade
+          to <literal>services.bird2</literal>.
+        </para>
+      </listitem>
       <listitem>
         <para>
           The options

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

@@ -178,6 +178,8 @@ In addition to numerous new and upgraded packages, this release has the followin
 
 - `tilp2` was removed together with its module
 
+- `bird1` and its modules `services.bird` as well as `services.bird6` have been removed. Upgrade to `services.bird2`.
+
 - The options `networking.interfaces.<name>.ipv4.routes` and `networking.interfaces.<name>.ipv6.routes` are no longer ignored when using networkd instead of the default scripted network backend by setting `networking.useNetworkd` to `true`.
 
 - MultiMC has been replaced with the fork PolyMC due to upstream developers being hostile to 3rd party package maintainers. PolyMC removes all MultiMC branding and is aimed at providing proper 3rd party packages like the one contained in Nixpkgs. This change affects the data folder where game instances and other save and configuration files are stored. Users with existing installations should rename `~/.local/share/multimc` to `~/.local/share/polymc`. The main config file's path has also moved from `~/.local/share/multimc/multimc.cfg` to `~/.local/share/polymc/polymc.cfg`.