Add notes about how LaunchTemplate changes are ignored unless you des…

…troy the stack and re-create it.

cdk/README.md

@@ -108,6 +108,10 @@ If your Batch job is stuck in the RUNNABLE state forever, use the
 * Insufficient service quotas for EC2 types (see `check-service-quotas.py`)
 * EC2 instance type unavailable (for rare EC2 types)
 
+Changes to the EC2 LaunchTemplate are ignored unless you completely destroy and re-deploy the stack (see [issue](https://github.com/aws/aws-cdk/issues/6686). Metrics data history will survive the apocalypse, so it's no big deal just annoying.
+
+If you need to update to the new latest Amazon Linux, you'll also need to destroy and re-deploy the stack. Otherwise it sticks with the version it was first deployed with.
+
 ## Architecture
 
 The requirements driving this architecture are:

cdk/s3_benchmarks/s3_benchmarks_stack.py

@@ -37,7 +37,8 @@ class S3ClientProps:
 ]
 
 # The "default" set of S3 clients to benchmark.
-# For now, only have the Canary test the CRT-based clients.
+# Only add clients under active development (e.g. CRT-based),
+# since each one adds significantly to execution time.
 DEFAULT_S3_CLIENTS = {
     'crt-c': S3ClientProps(color=cloudwatch.Color.RED),
     'crt-java': S3ClientProps(color=cloudwatch.Color.GREEN),