doc: add diagram to each example

besides readme

Author: iru

examples/single-account-ecs/README.md

@@ -3,7 +3,7 @@
 Deploy Sysdig Secure for Cloud in a single AWS account.<br/>
 All the required resources and workloads will be run under the same account.
 
-![single-account diagram](https://raw.githubusercontent.com/sysdiglabs/terraform-aws-secure-for-cloud/master/examples/single-account/diagram-single.png)
+![single-account diagram](https://raw.githubusercontent.com/sysdiglabs/terraform-aws-secure-for-cloud/master/examples/single-account-ecs/diagram-single.png)
 
 ## Prerequisites