Fix documentation to reflect changed file name

hftest_service.c was renamed to service.c in commit 3ad6e54.

Change-Id: I47b35bf200982cbec4785db078b98e5294149af1
diff --git a/docs/ b/docs/
index ae6e85a..6f889f8 100644
--- a/docs/
+++ b/docs/
@@ -23,7 +23,7 @@
         hypervisor, possibly communicating with a helper service in one or more
         secondary VMs.
     *   Using our own _hftest_ framework, with `standalone_main.c` for the
-        primary VM and `hftest_service.c` for secondary VMs.
+        primary VM and `service.c` for secondary VMs.
     *   Build own primary and secondary VMs, run in EL1 under actual Hafnium
 1.  Linux tests