supervisor cleanup, documentation and minor fixes

docs/architecture.md

@@ -0,0 +1,15 @@
+# Architecture
+
+The Horus architecture consists of three layers:
+
+1. Coordinator: A workflow engine that executes DAG-based flows by sending ready job steps to the targeted supervisors.
+2. Supervisor: A job dispatcher that routes jobs to the appropriate runners.
+3. Runner: A job executor that runs the actual job steps.
+
+## Networking
+
+- The user / client talks to the coordinator over an OpenRPC interface, using either regular HTTP transport or Mycelium.
+- The coordinator talks to the supervisor over an OpenRPC interface, using either regular HTTP transport or Mycelium.
+- The supervisor talks to runners over a Redis based job execution protocol.
+
+