Update README.md

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Author: rjwats

README.md

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 # ESP8266 React
 
+[![Build Status](https://travis-ci.org/rjwats/esp8266-react.svg?branch=master)](https://travis-ci.org/rjwats/esp8266-react)
+
 A simple, secure and extensible framework for IoT projects built on ESP8266/ESP32 platforms with responsive React front-end.
 
 Designed to work with the PlatformIO IDE with [limited setup](#getting-started). Please read below for setup, build and upload instructions.