Basic architecture documentation

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

ecs/README.md

@@ -1 +1,31 @@
 # Docker CLI plugin for Amazon ECS
+
+## Architecture
+
+ECS plugin is a [Docker CLI plugin](https://docs.docker.com/engine/extend/cli_plugins/)
+root command `ecs` require aws profile to get API credentials from `~/.aws/credentials`
+as well as AWS region - those will later be stored in a docker context
+
+A `compose.yaml` is parsed and converted into a [CloudFormation](https://aws.amazon.com/cloudformation/)
+template, which will create all resources in dependent order and cleanup on
+`down` command or deployment failure.
+
+```
+  +-----------------------------+
+  | compose.yaml file           |
+  +-----------------------------+
+- Load
+  +-----------------------------+
+  | compose-go Model            |
+  +-----------------------------+
+- Convert
+  +-----------------------------+
+  | CloudFormation Template     |
+  +-----------------------------+
+- Apply
+  +---------+      +------------+  
+  | AWS API |  or  | stack file |
+  +---------+      +------------+
+```
+
+(if this sounds familiar, see [Kompose](https://github.com/kubernetes/kompose/blob/master/docs/architecture.md))