Merge pull request twbs#18736 from twbs/readme-badges

README: Add badges for Packagist and Atmosphere

README.md

@@ -5,6 +5,8 @@
 [![npm version](https://img.shields.io/npm/v/bootstrap.svg)](https://www.npmjs.com/package/bootstrap)
 [![Build Status](https://img.shields.io/travis/twbs/bootstrap/master.svg)](https://travis-ci.org/twbs/bootstrap)
 [![devDependency Status](https://img.shields.io/david/dev/twbs/bootstrap.svg)](https://david-dm.org/twbs/bootstrap#info=devDependencies)
+[![Meteor Atmosphere](https://img.shields.io/badge/meteor-twbs%3Abootstrap-blue.svg)](https://atmospherejs.com/twbs/bootstrap)
+[![Packagist Prerelease](https://img.shields.io/packagist/vpre/twbs/bootstrap.svg)](https://packagist.org/packages/twbs/bootstrap)
 [![NuGet](https://img.shields.io/nuget/vpre/bootstrap.svg)](https://www.nuget.org/packages/bootstrap/4.0.0-alpha2)
 [![Selenium Test Status](https://saucelabs.com/browser-matrix/bootstrap.svg)](https://saucelabs.com/u/bootstrap)