website: redirect obsolete page to where the info now lives

templates/website/nginx/rewrite_rules.conf.erb

@@ -44,6 +44,7 @@ rewrite ^/contribute/how/donate/?$ /donate permanent;
 rewrite ^/contribute/how/user_interface(.*) /contribute/how/user_experience$1 permanent;
 rewrite ^/contribute/l10n_tricks/git-clean-po\.sh /contribute/l10n_tricks/git-clean-po permanent;
 rewrite ^/contribute/signing_key_revocation/?$ /doc/about/openpgp_keys/signing_key_revocation permanent;
+rewrite ^/contribute/working_together/document_progress/?$ "/contribute/working_together/GitLab#document-progress" permanent;
 rewrite ^/contribute/working_together/roles/front_desk/?$ /contribute/working_together/roles/help_desk permanent;
 rewrite ^/contribute/design/usb_installation/?$ /contribute/design/installation permanent;
 rewrite ^/customize/?$ /contribute/customize permanent;