Architecture.md

 This document describes the high-level blocks present in SysOTA.
 
+As of v0.1.0 SysOTA uses a service model, with `sysotad` presenting a set of D-Bus interfaces that the `sysotactl` and other programs interact with.
+
 # Boot Protocol
 
 Boot protocol defines how SysOTA interacts with the boot system. The protocol assumes the A/B update system.