Add reference to protobuf-d
https://github.com/dcarp/protobuf-d is a conformance tested proto3
runtime library and code generator for D.
diff --git a/docs/third_party.md b/docs/third_party.md
index 3f267dd..f11f0cb 100644
--- a/docs/third_party.md
+++ b/docs/third_party.md
@@ -25,6 +25,7 @@
* Clojure: http://github.com/ninjudd/clojure-protobuf
* Common Lisp: http://github.com/ndantam/s-protobuf
* Common Lisp: http://github.com/brown/protobuf
+* D: https://github.com/dcarp/protobuf-d
* D: https://github.com/msoucy/dproto
* D: http://256.makerslocal.org/wiki/index.php/ProtocolBuffer
* D: https://github.com/opticron/ProtocolBuffer
