correct url for package json file

Author: Christian Moll

README.md

@@ -22,7 +22,7 @@ Starting with 1.6.4, Arduino allows installation of third-party platform package
 
 - Install Arduino 1.6.8 from the [Arduino website](http://www.arduino.cc/en/main/software).
 - Start Arduino and open Preferences window.
-- Enter ```http://doku.kniwwelino.lu/_media/en/download/package_esp8266_kniwwelino.json``` into *Additional Board Manager URLs* field. You can add multiple URLs, separating them with commas.
+- Enter ```http://doku.kniwwelino.lu/_media/en/download/package_esp8266_kniwwelino_index.json``` into *Additional Board Manager URLs* field. You can add multiple URLs, separating them with commas.
 - Open Boards Manager from Tools > Board menu and install *esp8266* platform (and don't forget to select your ESP8266 board from Tools > Board menu after installation).
 
 The best place to ask questions related to this core is ESP8266 community forum: http://www.esp8266.com/arduino.
@@ -32,7 +32,7 @@ If you find this forum or the ESP8266 Boards Manager package useful, please cons
 #### Available versions
 
 ##### Stable version ![](http://arduino.esp8266.com/stable/badge.svg)
-Boards manager link: `http://doku.kniwwelino.lu/_media/en/download/package_esp8266_kniwwelino.json`
+Boards manager link: `http://doku.kniwwelino.lu/_media/en/download/package_esp8266_kniwwelino_index.json`
 
 Documentation: [http://esp8266.github.io/Arduino/versions/2.2.0/](http://esp8266.github.io/Arduino/versions/2.2.0/)