Add comment showing expected docker compose ps JSON format

[Copilot]

Description

Addresses review feedback from #13216 to add documentation showing the expected JSON format from docker compose ps --format json.

Added a comment in PrintEndpointsAsync showing:

• Example NDJSON output (one JSON object per line per container)
• Which fields are parsed: Service, Publishers[].TargetPort, Publishers[].PublishedPort

// Example output format:
// {"ID":"abc123","Name":"myapp-api-1","Command":"dotnet MyApp.dll","Project":"myapp","Service":"api","State":"running","Health":"","ExitCode":0,"Publishers":[{"URL":"","TargetPort":8080,"PublishedPort":5000,"Protocol":"tcp"}]}

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire-docs issue (consider using one of the following templates):
      • New (or update) doc-idea template
      • New breaking-change template
      • New diagnostic template
  • No

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