Update README.md (#7295)

Fix forgotten text edit for the latest version

Author: devyte

README.md

@@ -36,7 +36,7 @@ Starting with 1.6.4, Arduino allows installation of third-party platform package
 #### Latest release [![Latest release](https://img.shields.io/github/release/esp8266/Arduino.svg)](https://github.com/esp8266/Arduino/releases/latest/)
 Boards manager link: `https://arduino.esp8266.com/stable/package_esp8266com_index.json`
 
-Documentation: [https://arduino-esp8266.readthedocs.io/en/2.7.0/](https://arduino-esp8266.readthedocs.io/en/2.7.1/)
+Documentation: [https://arduino-esp8266.readthedocs.io/en/2.7.1/](https://arduino-esp8266.readthedocs.io/en/2.7.1/)
 
 ### Using git version
 [![Linux build status](https://travis-ci.org/esp8266/Arduino.svg)](https://travis-ci.org/esp8266/Arduino)