ocamlPackages.ocaml-lsp: wrap with dot-merlin-reader

this requires that dot-merlin-reader be built with the same ocaml version as
ocaml-lsp

pkgs/development/ocaml-modules/ocaml-lsp/default.nix

@@ -1,4 +1,4 @@
-{ buildDunePackage, jsonrpc, lsp }:
+{ buildDunePackage, jsonrpc, lsp, makeWrapper, dot-merlin-reader }:
 
 buildDunePackage {
   pname = "ocaml-lsp-server";
@@ -9,6 +9,12 @@ buildDunePackage {
 
   buildInputs = lsp.buildInputs ++ [ lsp ];
 
+  nativeBuildInputs = [ makeWrapper ];
+
+  postInstall = ''
+    wrapProgram $out/bin/ocamllsp --prefix PATH : ${dot-merlin-reader}/bin
+  '';
+
   meta = jsonrpc.meta // {
     description = "OCaml Language Server Protocol implementation";
   };