Update README.md (#29)

Adjusting naming standardisation in README. Oversight.

Author: eltontay-circle

README.md

@@ -15,8 +15,8 @@ This sample application demonstrates Cross-Chain Transfer Protocol (CCTP) step-b
 - Unichain Sepolia
 - Polygon PoS Amoy
 - Sei Testnet
-- XDC_TESTNET
-- PLUME_TESTNET 
+- XDC Testnet
+- Plume Testnet 
 
 ## Environment Setup