docs: remove discarded build status badge (#2601)

README.md

@@ -1,13 +1,11 @@
 # Nock
 
 [![npm](https://img.shields.io/npm/v/nock.svg)][npmjs]
-[![Build Status](https://travis-ci.org/nock/nock.svg)][build]
 ![Coverage Status](http://img.shields.io/badge/coverage-100%25-brightgreen.svg)
 [![Backers on Open Collective](https://opencollective.com/nock/backers/badge.svg)](#backers)
 [![Sponsors on Open Collective](https://opencollective.com/nock/sponsors/badge.svg)](#sponsors)
 
 [npmjs]: https://www.npmjs.com/package/nock
-[build]: https://travis-ci.org/nock/nock
 
 > **Notice**
 >