Minor modification to the README file

Qualify Base and Foundation FVPs as "Armv8 Architecture FVPs", to align
with the terminology used on this page:
https://developer.arm.com/products/system-design/fixed-virtual-platforms

Change-Id: Iabdcc37e0ef25373a3d4bb7d1ad964ea53e009a5
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
diff --git a/readme.rst b/readme.rst
index 9d71f8c..b27a070 100644
--- a/readme.rst
+++ b/readme.rst
@@ -72,11 +72,11 @@
 the `Juno Arm Development Platform`_. The AArch32 build has only been tested on
 variant r0.
 
-Arm Fixed Virtual Platforms
-'''''''''''''''''''''''''''
+Armv8 Architecture Fixed Virtual Platforms
+''''''''''''''''''''''''''''''''''''''''''
 
-The AArch64 build has been tested on the following Arm Fixed Virtual Platforms
-(`FVP`_):
+The AArch64 build has been tested on the following Armv8 Architecture Fixed
+Virtual Platforms (`FVP`_):
 
 -  ``FVP_Base_AEMv8A-AEMv8A``
 -  ``FVP_Base_Cortex-A35x4``