wlr-randr: build man pages (#465061)

pkgs/by-name/wl/wlr-randr/package.nix

@@ -5,6 +5,7 @@
   meson,
   ninja,
   pkg-config,
+  scdoc,
   wayland,
   wayland-scanner,
 }:
@@ -26,6 +27,7 @@ stdenv.mkDerivation rec {
     meson
     ninja
     pkg-config
+    scdoc
     wayland-scanner
   ];
   buildInputs = [ wayland ];
@@ -33,6 +35,11 @@ stdenv.mkDerivation rec {
     pkg-config
   ];
 
+  outputs = [
+    "out"
+    "man"
+  ];
+
   meta = with lib; {
     description = "Xrandr clone for wlroots compositors";
     homepage = "https://gitlab.freedesktop.org/emersion/wlr-randr";