Improve --stream-delivery-resources JSON example discoverability in CLI help and command docs

[aidandaly24]

Description

The --stream-delivery-resources <json> flag on agentcore add memory accepts a complex JSON structure, but the expected format is hard to discover:

• CLI help text (agentcore add memory --help): Only says "Stream delivery config as JSON string (advanced, overrides flat flags)" — no example
• docs/commands.md: Lists the flag in a table but does NOT show the JSON structure
• docs/memory.md: Has the full example (line 253), but users following the command reference won't find it

Valid JSON structure (for reference):

{
 "resources": [
 {
 "kinesis": {
 "dataStreamArn": "arn:aws:kinesis:us-west-2:123456789012:stream/my-stream",
 "contentConfigurations": [
 {
 "type": "MEMORY_RECORDS",
 "level": "FULL_CONTENT"
 }
 ]
 }
 }
 ]
}

Note on CloudWatch

The original report mentioned "no default CloudWatch log group for memory." This is not a CLI issue — the CLI has always been Kinesis-only for memory stream delivery (since the feature was introduced in PR #531/#534). There is no git history of CloudWatch ever being a memory delivery target in the CLI. This may be a confusion with the Starter Toolkit, which has different behavior. The CLI schema explicitly notes that Kinesis is currently the only supported delivery type.

Acceptance Criteria

• agentcore add memory --help includes a compact JSON example or pointer to docs for --stream-delivery-resources
• docs/commands.md includes the JSON example inline or cross-references docs/memory.md

[aidandaly24]

Closing — the JSON example already exists in docs/memory.md. Surfacing it in --help and commands.md is cosmetic and not worth the review overhead.