Added Embedded Proto to third_party.md.

docs/third_party.md

@@ -18,6 +18,7 @@ These are projects we know about implementing Protocol Buffers for other program
 * C: https://github.com/squidfunk/protobluff
 * C: https://github.com/eerimoq/pbtools
 * C++: https://github.com/google/protobuf (Google-official implementation)
+* C++: https://EmbeddedProto.com
 * C/C++: http://spbc.sf.net/
 * C#: http://code.google.com/p/protobuf-csharp-port
 * C#: https://silentorbit.com/protobuf/