[Docs] Illustrate cloud/identity/organizations with Orbital Labs and Stellar Dynamics examples

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Overview

Update cloud/identity/organizations to use Orbital Labs and Stellar Dynamics as example organizations, replacing generic placeholders.

Tasks

• Add Orbital Labs as the example org in the org-creation walkthrough
• Add Stellar Dynamics as the enterprise tenant example (cross-org access scenario)
• Reference Constellation Cloud as the provider/MSP
• Link to /cloud/about for full narrative context

Reference

• Narrative: /cloud/about
• Difficulty: Low