GPC-NONE: Update architecture summary (#2392)

Update doc/architecture/architecture.md

Co-authored-by: Ethan Mills <ethan.mills@digital.cabinet-office.gov.uk>

doc/architecture/architecture.md

@@ -3,37 +3,33 @@
 This is a summary of the ADRs across the service, trying to produce a single consolidated view of the as-is system.
 
 ## AWS/Infrastructure
+
 A current state view of the overall system architecture and services used in AWS is documented below.
 
-![](img/architecture.drawio.svg)
+![Architecture Diagram](img/architecture.drawio.svg)
 
 ## Stubs/additional services
 
 We currently have a fake version of the supplier side (HMPO), running as
-- a mock API to look up against in AWS AppRunner
-- a mock event API calling the service in AWS Lambda
 
-We also have a mock consumer running as
-- a set of Step Functions calling the API
+- a Lambda to fetch a file from the GRO SFTP Host
+- Mapped using step functions into individual API calls into the CloudFront front end
 
 ## Load/Volumes
 
 We're currently working with a limited data set of notifications of death.
 Using ONS data, we've worked out what an "average" day looks like, and are targetting ~3,000 notifications a day.
 
-We're currently working with one data acquirer, and one data supplier, as well as an internal mock acquirer,
-so the total data volumes are relatively low currently.
+We're currently working with one data acquirer, and one data supplier, so the total data volumes are relatively low currently.
 
 ## Event flow
-Events flow through the system as shown in the diagram below.
-
-![flow.drawio.svg](img/event-flow.drawio.svg)
 
-Each supplier event may result in several acquirer events as the system fans out. These are decoupled from each other early
-in the process, and queues are used to provide resiliency. Each supplier event is given an ID, which can be linked to
-audit information.
+The data model and event process is described in [TechDocs](https://docs.life-events.dev.account.gov.uk/data-model.html).
 
 ## Data flow
+
 The data flow is illustrated below.
 
 ![data-flow.drawio.svg](img/data-flow.drawio.svg)
+
+More detailed data retention policies can be found in our [Data Retention Policy](https://docs.life-events.dev.account.gov.uk/data-retention-policy.html).