programs.home-manager.enable = true does not work as expected in NixOS

**Describe the bug** According to the code of home-manager/modules/programs/home-manager.nix https://github.com/nix-community/home-manager/blob/529d2aac542a42c57d4b765501ace564b07e3d99/modules/programs/home-manager.nix#L31C1-L33C5 When use home-manager as a nixos module, `home-manager` command will not be installed. Therefore, I think the description in the guide might be misleading. ```nix # Let Home Manager install and manage itself. programs.home-manager.enable = true; ```