nixos/*: automatically convert option descriptions

conversions were done using https://github.com/pennae/nix-doc-munge
using (probably) rev f34e145 running

    nix-doc-munge nixos/**/*.nix
    nix-doc-munge --import nixos/**/*.nix

the tool ensures that only changes that could affect the generated
manual *but don't* are committed, other changes require manual review
and are discarded.

nixos/modules/hardware/uinput.nix

@@ -4,7 +4,7 @@ let
   cfg = config.hardware.uinput;
 in {
   options.hardware.uinput = {
-    enable = lib.mkEnableOption "uinput support";
+    enable = lib.mkEnableOption (lib.mdDoc "uinput support");
   };
 
   config = lib.mkIf cfg.enable {