updated README

Signed-off-by: Konstantin Gizdov <kgizdov@gmail.com>

Author: kgizdov

README.md

@@ -1,4 +1,6 @@
 # CERN ROOT 6
 ROOT 6 with custom options to accommodate Arch Linux and GCC 6.2
 
-AUR Package available [here](https://aur.archlinux.org/packages/root/)
+Base AUR package available [here](https://aur.archlinux.org/packages/root/)
+
+AUR package with XROOTD available [here](https://aur.archlinux.org/packages/root-extra/)