Remove an unnecessary badge

Author: d-frey

README.md

@@ -4,7 +4,6 @@
 [![TravisCI](https://travis-ci.org/taocpp/json.svg)](https://travis-ci.org/taocpp/json)
 [![AppVeyor](https://ci.appveyor.com/api/projects/status/github/taocpp/json?svg=true)](https://ci.appveyor.com/project/taocpp/json)
 [![Coverage](https://img.shields.io/coveralls/taocpp/json.svg)](https://coveralls.io/github/taocpp/json)
-[![Issues](https://img.shields.io/github/issues/taocpp/json.svg)](https://github.com/taocpp/json/issues)
 
 The Art of C++ / JSON is a zero-dependency C++11 header-only library that provides a generic JSON value object, conversions from and to JSON string representation, and supports JSON Pointer and JSON Patch. It is designed for correctness and simplicity, is based on C++ standard containers, and strives for speed through minimalism (rather than complicated optimisations).