v1.15.1

• Adjust keyPrefix() with DoubleMap args (Thanks to https://github.com/KiChjang)
• Added WeightToFeeCoefficient type (Thanks to https://github.com/danforbes)
• Spelling fixes for console logs (Thanks to https://github.com/JoshOrndorff)
• Spelling fixes in cookbook (Thanks to https://github.com/pawelnguyen)
• Add transactionVersion getter in payloads (Thanks to https://github.com/amaurymartiny)
• Adjust stakerRewards derive ordering for improved on-payout refreshes
• Baseline implementation for derive caching infrastructure
• Adjust Multiplier type to Fixed128 (as per latest Substrate)
• Updated to latest Substrate metadata & add new types