docs: Remove obsolete ShellRecorder include

It joined the invisible choir, so trying to build with gtk-docs
enabled is currently broken (mea culpa for not having caught that
during distcheck).

https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1448

docs/reference/shell/shell-docs.sgml

@@ -36,10 +36,6 @@
     <xi:include href="xml/shell-tray-icon.xml"/>
     <xi:include href="xml/shell-tray-manager.xml"/>
   </chapter>
-  <chapter>
-    <title>Recorder</title>
-    <xi:include href="xml/shell-recorder.xml"/>
-  </chapter>
   <chapter>
     <title>Integration helpers and utilities</title>
     <xi:include href="doc-gen-org.gnome.Shell.SearchProvider.xml"/>