Add doc about running tests on FVP.

Change-Id: I29063eb7a0ef66f9093740c158cff15512ed15d2
diff --git a/docs/Testing.md b/docs/Testing.md
index 8a33ee2..b7b8c93 100644
--- a/docs/Testing.md
+++ b/docs/Testing.md
@@ -52,7 +52,8 @@
 ## QEMU tests
 
 These tests boot Hafnium on QEMU and the VMs make calls to Hafnium to test its
-behaviour.
+behaviour. They can also be run on the Arm [FVP](FVP.md) and in some cases on
+real hardware.
 
 ### hftest