nixos: Fix build of manual
nixos: Fix build of manual

XML error introduced with merge commit 4e0fea3fe294d112ac6eef5adbed2357.

This was probably because of wrong conflict resolution, because the
actual change (d8e697b4fcfd929d05221ac3e67b9c04ac69df86) had the close
tag of the <para/> element, but the merge commit didn't.

Signed-off-by: aszlig <ee1aa092358634f9c53f01b5a783726c9e21b35a@nix.build>

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs