ARM is now Arm.

Change-Id: Ib272ebd46423dd1a84605abe3d6d2fe0c729b76a
diff --git a/docs/VmInterface.md b/docs/VmInterface.md
index bc66aa4..47de251 100644
--- a/docs/VmInterface.md
+++ b/docs/VmInterface.md
@@ -79,7 +79,7 @@
 ## Performance counters
 
 VMs will be blocked from accessing performance counter registers (for the
-performance monitor extensions described in chapter D5 of the ARMv8-A reference
+performance monitor extensions described in chapter D5 of the Armv8-A reference
 manual) in production, to prevent them from being used as a side channel to leak
 data between VMs.