maint: update badges in README.md
@@ -5,7 +5,7 @@ By the [luaposix project][github]
[![License](http://img.shields.io/:license-mit-blue.svg)](http://mit-license.org)
[![travis-ci status](https://secure.travis-ci.org/luaposix/luaposix.png?branche=master)](http://travis-ci.org/luaposix/luaposix/builds)
-[![Stories in Ready](https://badge.waffle.io/luaposix/luaposix.png?label=ready&title=Ready)](https://waffle.io/luaposix/luaposix)
+[![codecov.io](https://codecov.io/github/luaposix/luaposix/coverage.svg?branch=master)](https://codecov.io/github/luaposix/luaposix?branch=master)
This is a POSIX binding for LuaJIT, [Lua][] 5.1, 5.2 and 5.3; like most
libraries it simply binds to C APIs on the underlying system, so it
