Neovim plugins missing help files

I installed neovim and nvim-cmp (among other plugins) using home-manager and nvim-cmp appears to be missing help files. :help cmp or :help nvim-cmp does not show the help for nvim-cmp.

I can load cmp without any issues with :lua require'cmp'

:scriptnames also show the path for cmp /nix/store/b1ayjwbikn0n7s0fayjc88qqj68kz3yn-luascm.1-nvim-cmp-2023-02-18/plugin/cmp.lua.

Why is there no help?

Hosted by Flying Circus.