doc: terminology cleanup in DM readme
Replace SOS or Service OS with Service VM
Clean up some of the grammar
@@ -3,10 +3,10 @@ ACRN Device Model
Introduction
============
+
The ACRN Device Model provides **device sharing** capabilities between the
-Service OS and Guest OSs. It is a component that is used in conjunction with
-the `ACRN Hypervisor`_ and this is installed within the Service OS. You can
-find out more about Project ACRN on the `Project ACRN documentation`_ website.
+Service VM and post-launched User VMs. It is a component that is used in
+conjunction with the `ACRN Hypervisor`_ and is installed within the Service
+VM.
.. _`ACRN Hypervisor`: https://github.com/projectacrn/acrn-hypervisor
-.. _`Project ACRN documentation`: https://projectacrn.github.io/
