SW-90: added plantuml example

SAS/ResourceAssignment/OTDBtoRATaskStatusPropagator/doc/otdb_to_ra_task_status_propagator.md

@@ -12,9 +12,24 @@ Due to historical reasons Lofar tracks it's tasks in three different databases:
 -  Jorrit Schaap schaap@astron.nl
 
 ### Overview
-- *Add a diagram*
-- *Add a link to the overview diagram*
-- *Add a link in the overview diagram to link back to this documentation*.
+
+TODO: do we want diagrams like this? If so, extend diagram with full sequence.
+
+@startuml
+title OTDB to RA task status propagator sequence diagram
+
+participant lofar.otdb.notification as lon
+control "OTDB to RA task status propagator" as otrtsp
+participant lofar.ra.command as lrc
+
+note over lon
+qpid exchange
+end note
+
+note over lrc
+qpid exchange
+end note
+@enduml
 
 - - -