docs: Update Strata devnet status

[john-light]

Description

Updates the doc to note that the devnet is now live!

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Type of Change

• New Document
• Update to Existing Document
• Bug Fix
• Question/clarification
• CI/CD Pipeline
• New or updated tests
• Other (please describe):

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Checklist

• I have reviewed the existing documentation to avoid duplication.
• The new or updated document includes clear and concise information.
• All relevant sections (e.g., introduction, usage examples, references)
  are included.
• The document follows the project's style guide and formatting rules.
• I have included any necessary references or external resources.
• Spellcheck and grammar check have been performed.
• (For updates) I have verified that the changes reflect the current state
  of the project.

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Thank you for contributing to our documentation!