Update boards_manager.md

docs/arduino-ide/boards_manager.md

-Installation instructions using Arduino IDE Boards Manager
-==========================================================
+## Installation instructions using Arduino IDE Boards Manager
+### ==========================================================
 
-Starting with 1.6.4, Arduino allows installation of third-party platform packages using Boards Manager. We have packages available for Windows, Mac OS, and Linux (32 and 64 bit).
+- Stable release link: `https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json`
+- Development release link: `https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_dev_index.json`
+
+Starting with 1.6.4, Arduino allows installation of third-party platform packages using Boards Manager. We have packages available for Windows, Mac OS, and Linux (32, 64 bit and ARM).
 
 - Install the current upstream Arduino IDE at the 1.8 level or later. The current version is at the [Arduino website](http://www.arduino.cc/en/main/software).
 - Start Arduino and open Preferences window.
-- Enter `https://espressif.github.io/arduino-esp32/package_esp32_index.json` or `https://espressif.github.io/arduino-esp32/package_esp32_dev_index.json` into *Additional Board Manager URLs* field. You can add multiple URLs, separating them with commas.
+- Enter one of the release links above into *Additional Board Manager URLs* field. You can add multiple URLs, separating them with commas.
 - Open Boards Manager from Tools > Board menu and install *esp32* platform (and don't forget to select your ESP32 board from Tools > Board menu after installation).
-
-Stable release link: `https://espressif.github.io/arduino-esp32/package_esp32_index.json`
-
-Development release link: `https://espressif.github.io/arduino-esp32/package_esp32_dev_index.json`