Update the architecture diagram

- Also update the instructions for editing the documentation images

README.md

@@ -30,9 +30,7 @@ distributions to make authentication possible.
 
 To learn more, see [architecture.md](doc/architecture.md).
 
-#### Example Deployment Architecture
-
-![example-deployment-architecture](doc/img/pinniped-architecture.svg)
+<img src="doc/img/pinniped_architecture.svg" alt="Pinniped Architecture Sketch" width="300px"/>
 
 ## Trying Pinniped
 

doc/architecture.md

@@ -10,6 +10,8 @@ relationship) and returns a credential which is understood by the host
 Kubernetes cluster. To learn more about this integration, see [Cluster
 Integration Strategies](#cluster-integration-strategies).
 
+<img src="img/pinniped_architecture.svg" alt="Pinniped Architecture Sketch" width="300px"/>
+
 ## External Identity Provider Integrations
 
 Pinniped will consume identity from one or more external identity providers
@@ -61,7 +63,3 @@ built with the [Pinniped Go client library](generated).
 ## Example Cluster Authentication Sequence Diagram
 
 ![example-cluster-authentication-sequence-diagram](img/pinniped.svg)
-
-## Example Deployment Architecture
-
-![example-deployment-architecture](img/pinniped-architecture.svg)

doc/img/README.md

@@ -1,8 +1,12 @@
-# README
+# `doc/img` README
 
-Note! Some of the image files in this directory (e.g.,
-[pinniped.svg](pinniped.svg)) were generated using
-[`plantuml`](https://plantuml.com/). To use `plantuml` to regenerate the image
-files, you simply run `plantuml -tsvg <file.txt>` from this directory. For
-example, to regenerate [pinniped.svg](pinniped.svg), run `plantuml -tsvg
-pinniped.txt`.
+## How to Update these Images
+
+- [pinniped.svg](pinniped.svg) was generated using [`plantuml`](https://plantuml.com/).
+  To regenerate the image, run `plantuml -tsvg pinniped.txt` from this directory.
+
+- [pinniped_architecture.svg](pinniped_architecture.svg) was created on [draw.io](https://draw.io).
+  It can be opened again for editing on that site by choosing "File" -> "Open from" -> "Device".
+  Because it includes embedded icons it should be exported using "File" -> "Export as" -> "SVG",
+  with the "Transparent Background", "Embed Images", and "Include a copy of my diagram" options
+  checked. The icons in this diagram are from their "CAE" shapes set.