removes paymasters

Author: cooganb

docs/pos/payments/transfers/transfer-usdc.md

@@ -57,7 +57,11 @@ main();
 
 Gateway collects USDC balances across any chain with USDC. Users need to send USDC to the Gateway Wallet (not an ERC-20), [more details here.](https://developers.circle.com/gateway#setting-up-a-balance)     
 
-Once the users have a balance, they can send 
+Once the users have a balance, they can send USDC to any chain using the Gateway implementation.
+
+## Prerequisites
+
+The follow example requires a Circle API key, which you can create through [the Circle Developer dashboard.](https://console.circle.com/) (You do not need a Cirlce business license to get a sandbox API key).
 
 ```ts