Adjust "how to expand storage" section numbers

[wwarriner]

What would you like to see added?

• Vendor quotes are now only good for 2 business days, instead of the original 30 calendar days.
• Add a part about the rapid recent increase in costs. Don't give dollar amounts, only note that the cost of a storage node has risen almost 50% between start of Dec 2025 and end of Feb 2026.