[Power BI] Document how to configure auto refresh in Power BI

[flanakin]

⚠️ Problem

^{Originally posted by simonarbel December 30, 2024}

Had to scratch my head over way to configure auto refresh in the published dashboards from the storage account and eventually found a solution.

🛠️ Solution

^{Originally posted by simonarbel December 30, 2024}

Please update the documentation accordingly as no reference for that.

See attached solution: Cost summary refresh instructions.docx

ℹ️ Additional context

Originally discussed in #1228

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