Update FinOps hub deployment files and changelog

[flanakin]

🛠️ Description

Update v13 deployment files

📋 Checklist

🔬 How did you test this change?

• 🤏 Lint tests
• 🤞 PS -WhatIf / az validate
• 👍 Manually deployed + verified
• 💪 Unit tests
• 🙌 Integration tests

🙋‍♀️ Do any of the following that apply?

• 🚨 This is a breaking change.
• 🤏 The change is less than 20 lines of code.

📑 Did you update docs/changelog.md?

• ✅ Updated changelog (required for dev PRs)
• ➡️ Will add log in a future PR (feature branch PRs only)
• ❎ Log not needed (small/internal change)

📖 Did you update documentation?

• ✅ Public docs in docs (required for dev)
• ✅ Public docs in docs-mslearn (required for dev)
• ✅ Internal dev docs in docs-wiki (required for dev)
• ✅ Internal dev docs in src (required for dev)
• ➡️ Will add docs in a future PR (feature branch PRs only)
• ❎ Docs not needed (small/internal change)

[Copilot]

Pull request overview

Adds a documented patch release entry for FinOps hubs v13 to the Microsoft Learn changelog, clarifying a managed exports fix and a related PowerShell deployment fix.

Changes:

• Adds a new “v13 Update 1” section with release date and fix notes for FinOps hubs and the PowerShell module.
• Moves the previously listed unreleased FinOps hubs fix into the v13 Update 1 release notes (and comments out the “Unreleased” section).