asciidoctor: expose all the bins

asciidoctor has multiple binaries, expose them all to the user

pkgs/tools/typesetting/asciidoctor/default.nix

@@ -1,12 +1,18 @@
-{ stdenv, lib, bundlerEnv, ruby, curl }:
-
-bundlerEnv {
-  pname = "asciidoctor";
+{ stdenv, lib, bundlerApp, ruby, curl }:
 
+bundlerApp {
   inherit ruby;
-
+  pname = "asciidoctor";
   gemdir = ./.;
 
+  exes = [
+    "asciidoctor"
+    "asciidoctor-bespoke"
+    "asciidoctor-latex"
+    "asciidoctor-pdf"
+    "asciidoctor-safe"
+  ];
+
   meta = with lib; {
     description = "A faster Asciidoc processor written in Ruby";
     homepage = http://asciidoctor.org/;