fix: add missing GitBook icons to fiat-moonpay module and changelog

Created by: gatteo

Summary

• Add missing GitBook-compatible icons to fiat-moonpay module pages to match other modules like wallet-btc
• Add changelog icon for better navigation visibility
• Fix dates in changelog

Changes

• sdk/fiat-modules/fiat-moonpay/configuration.md → icon: gear
• sdk/fiat-modules/fiat-moonpay/usage.md → icon: book-open
• sdk/fiat-modules/fiat-moonpay/api-reference.md → icon: code
• overview/changelog.md → icon: clock-rotate-left