chore: Added Appveyor badge.

README.md

@@ -3,6 +3,7 @@
 [![NPM Version][npm-image]][npm-url]
 [![NPM Downloads][downloads-image]][downloads-url]
 [![Travis CI Build][travis-image]][travis-url]
+[![Appveyor CI Build][appveyor-image]][appveyor-url]
 [![Test Coverage][coveralls-image]][coveralls-url]
 [![Greenkeeper badge][greenkeeper-image]][greenkeeper-url]
 [![Deps][david-image]][david-url]
@@ -235,8 +236,10 @@ MIT
 [npm-url]: https://npmjs.org/package/snooplogg
 [downloads-image]: https://img.shields.io/npm/dm/snooplogg.svg
 [downloads-url]: https://npmjs.org/package/snooplogg
-[travis-image]: https://img.shields.io/travis/cb1kenobi/snooplogg.svg
+[travis-image]: https://travis-ci.org/cb1kenobi/snooplogg.svg?branch=master
 [travis-url]: https://travis-ci.org/cb1kenobi/snooplogg
+[appveyor-image]: https://ci.appveyor.com/api/projects/status/ecpifaqt54itg7h4?svg=true
+[appveyor-url]: https://ci.appveyor.com/project/cb1kenobi/snooplogg
 [coveralls-image]: https://img.shields.io/coveralls/cb1kenobi/snooplogg/master.svg
 [coveralls-url]: https://coveralls.io/r/cb1kenobi/snooplogg
 [greenkeeper-image]: https://badges.greenkeeper.io/cb1kenobi/snooplogg.svg