How to use `redirects` for nixos docs?

I’m trying to add a doc.md for the crowdsec module, however I’m getting the following error message:

error: builder for '/nix/store/zg5rqdr7nr6mdb9ggy4q1nhscpsc768f-nixos-manual-html.drv' failed with exit code 1;
       last 25 log lines:
       >     - sec-crowdsec-reset
       >
       > This can happen when an identifier was added, renamed, or removed.
       >
       >     Added new content?
       >         $ redirects add-content <identifier> <path>
       >     often:
       >         $ redirects add-content <identifier> index.html
       >
       >     Moved existing content to a different output path?
       >         $ redirects move-content <identifier> <path>
       >
       >     Renamed existing identifiers?
       >         $ redirects rename-identifier <old-identifier> <new-identifier>
       >
       >     Removed content? Redirect to alternatives or relevant release notes.
       >         $ redirects remove-and-redirect <identifier> <target-identifier>
       >
       >     NOTE: Run the right nix-shell to make this command available.
       >         Nixpkgs:
       >         $ nix-shell doc
       >         NixOS:
       >         $ nix-shell nixos/doc/manual
       >
       > NOTE: If your build passes locally and you see this message in CI, you probably need a rebase.

But I don’t understand what <path> should be. Is it the source path where <identifier> is declared? Is it the destination path for a file which will be changed to include <identifier>?
It says that it’s often index.html but fd index.html just returns nixos/tests/kiwix-serve/html/index.html for me.

What do I have to do?

Context

Here’s the relevant PR-message: https://github.com/NixOS/nixpkgs/pull/535319#discussion_r4080042953