removed doc.go from module path, as go tool doesn't support package names which are reserved keywords

Updates #291

doc.go

@@ -1,11 +0,0 @@
-// Copyright (c) 2012-2018 Ugorji Nwoke. All rights reserved.
-// Use of this source code is governed by a MIT license found in the LICENSE file.
-
-/*
-Package go is an empty holder package for go-codec.
-
-This doc.go is here just to support tools that have problems with empty packages.
-
-DO NOT USE THIS PACKAGE DIRECTLY.
-*/
-package go