docs: improve deploy instructions (#26)

Closes EFI-477

Author: 0xAustrian

README.md

@@ -120,30 +120,38 @@ yarn test:bulloak:fix
 
 ## Deploy & verify
 
-### Setup
-
-Configure the `.env` variables and source them:
+### 1) Configure the `.env` variables and source them:
 
 ```bash
 source .env
 ```
 
-Import your private keys into Foundry's encrypted keystore:
+`$MAINNET_DEPLOYER_NAME` and `$SEPOLIA_DEPLOYER_NAME` are the names of the private keys in the keystore.
+
+`$ETHERSCAN_API_KEY` is required for the deployment to be verified on Etherscan.
+
+### 2) Import your private keys into Foundry's encrypted keystore:
 
 ```bash
 cast wallet import $MAINNET_DEPLOYER_NAME --interactive
 ```
 
+or
+
 ```bash
 cast wallet import $SEPOLIA_DEPLOYER_NAME --interactive
 ```
 
+### 3) Call the deploy script:
+
 ### Sepolia
 
 ```bash
 yarn deploy:sepolia
 ```
 
+or
+
 ### Mainnet
 
 ```bash