Updated board manager URL

Author: j54n1n

README.md

@@ -11,7 +11,7 @@ recommended and required.
 This installation method requires Arduino IDE version 1.6.11 or greater.
 * Open the Arduino IDE.
 * Open the **File > Preferences** menu item.
-* Enter the following URL in **Additional Boards Manager URLs**: `https://j54n1n.github.io/arduinorobot/package_j54n1n_arduinorobot_index.json`
+* Enter the following URL in **Additional Boards Manager URLs**: `https://rainerum-robotics-arduino.github.io/arduinorobot/package_j54n1n_arduinorobot_index.json`
 * Open the **Tools > Board > Boards Manager...** menu item.
 * Wait for the platform indexes to finish downloading.
 * Scroll down until you see the **Arduino Robot Boards** entry and click on it.