Update README with Sepolia contract addresses

Added Sepolia testnet contract addresses for OrderContract, MerchantNft, and A3AToken.

Author: realkingaxel

README.md

@@ -10,8 +10,11 @@ Orders, validation, and settlement all happen transparently on-chain — powered
 * **A3AToken** → handles platform fees and incentives
 
 > 🧩 All contracts are **deployed and verified on Sepolia** testnet.
+>
 > OrderContract Sepolia: 0x1417178178d35E5638c30B4070eB4F4ccC0aEaD0
+>
 > MerchantNft Sepolia: 0xe2d8c380db7d124D03DACcA07645Fea659De9738
+>
 > A3AToken Sepolia: 0xE643887beaE652270d071D61F8d1F900A02b550C
 
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