update certifications rule (PR from TinaCMS)

[tinacloud-app]

We did not have a rule about Microsoft certifications.
Re-purposing this outdated Power Platform-specific rule to create one.

[github-actions]

🔍 Preview PR Changes

View updated pages in edit mode:

• Rules to Better System Administrators
• Rules to Better Azure
• Rules to Better Power Platform
• Do you know the relevant Microsoft certifications and associated exams?

Branch: tina/update-certifications-rule

[github-actions]

👋 Hi @chrisschultzssw,

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