Fix formatting in README.md (facebook#21186)

Summary:
This PR fixes the formatting of the AppVeyor badge in `README.md` to remove a stray newline that broke formatting.
Pull Request resolved: facebook#21186

Differential Revision: D9932191

Pulled By: hramos

fbshipit-source-id: f87ad7664d6a0b288615f473ba38b4734b41eb88

README.md

@@ -1,5 +1,4 @@
-# [React Native](https://facebook.github.io/react-native/) ·  [![Circle CI Status](https://circleci.com/gh/facebook/react-native.svg?style=shield)](https://circleci.com/gh/facebook/react-native) [![Build status](https://ci.appveyor.com/api/projects/status/g8d58ipi3auqdtrk/branch/master?svg=true
-)](https://ci.appveyor.com/project/facebook/react-native/branch/master) [![npm version](https://badge.fury.io/js/react-native.svg)](https://badge.fury.io/js/react-native) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md#pull-requests)
+# [React Native](https://facebook.github.io/react-native/) ·  [![Circle CI Status](https://circleci.com/gh/facebook/react-native.svg?style=shield)](https://circleci.com/gh/facebook/react-native) [![Build status](https://ci.appveyor.com/api/projects/status/g8d58ipi3auqdtrk/branch/master?svg=true)](https://ci.appveyor.com/project/facebook/react-native/branch/master) [![npm version](https://badge.fury.io/js/react-native.svg)](https://badge.fury.io/js/react-native) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md#pull-requests)
 
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