Update README.md

Remove references to old, dysfunctional CI systems

Author: andreasbuhr

README.md

@@ -85,10 +85,6 @@ proposal.
 It has been open-sourced in the hope that others will find it useful and that the C++ community
 can provide feedback on it and ways to improve it.
 
-It requires a compiler that supports the coroutines TS:
-- Windows + Visual Studio 2017 [![Windows Build Status](https://ci.appveyor.com/api/projects/status/github/lewissbaker/cppcoro?branch=master&svg=true&passingText=master%20-%20OK&failingText=master%20-%20Failing&pendingText=master%20-%20Pending)](https://ci.appveyor.com/project/lewissbaker/cppcoro/branch/master)
-- Linux + Clang 5.0/6.0 + libc++ [![Build Status](https://travis-ci.org/lewissbaker/cppcoro.svg?branch=master)](https://travis-ci.org/lewissbaker/cppcoro)
-
 The Linux version is functional except for the `io_context` and file I/O related classes which have not yet been implemented for Linux (see issue [#15](https://github.com/lewissbaker/cppcoro/issues/15) for more info).
 
 # Class Details