Documentation updated

Author: rsta2

CREDITS

@@ -14,3 +14,6 @@ Spanish keymap (taken from Circle)
 Joshua Otto
 Providing support for framebuffers where pitch != width * bytes per pixel
 USB MIDI device class support
+
+Paolo Franchetti
+Suggesting improvements for the HID class device support and testing

README.md

@@ -58,6 +58,8 @@ Another option (NDEBUG) can be defined in Rules.mk to build the release version.
 Building
 --------
 
+> For AArch64 support go to the end of this file.
+
 Building is normally done on PC Linux. If building for the Raspberry Pi 1 you need a [toolchain](http://elinux.org/Rpi_Software#ARM) for the ARM1176JZF core. For Raspberry Pi 2/3 you need a toolchain with Cortex-A7/-A53 support. A toolchain, which works for all of these, can be downloaded [here](https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads). USPi has been tested with the version *7-2018-q2-update* from this website. You can also build USPi on the Raspberry Pi itself on Raspbian.
 
 First edit the file *Rules.mk* and set the Raspberry Pi version (*RASPPI*, 1, 2 or 3) and the *PREFIX* of your toolchain commands. Alternatively you can create a *Config.mk* file (which is ignored by git) and set the Raspberry Pi version and the *PREFIX* variable to the prefix of your compiler like this (don't forget the dash at the end):