Update .env.template to reorder variable for better clarity

.env.template

@@ -1,18 +1,18 @@
+# The mnemonic phrase used to derive the wallet's private keys
+# MNEMONIC=...
+
 # Index of the account generated from the mnemonic to be used as the Voucher Manager
 # IEXEC_VOUCHER_MANAGER_ACCOUNT_INDEX=...
 
 # Index of the account generated from the mnemonic to be used as the Voucher Minter
 # IEXEC_VOUCHER_MINTER_ACCOUNT_INDEX=...
 
-# Flag to indicate whether to use a local blockchain fork (set to 'true' for local fork development)
-# IS_LOCAL_FORK=...
-
-# The mnemonic phrase used to derive the wallet's private keys
-# MNEMONIC=...
-
 # The private key for accessing the production account
 # PROD_PRIVATE_KEY=...
 
+# Flag to indicate whether to use a local blockchain fork (set to 'true' for local fork development)
+# IS_LOCAL_FORK=...
+
 # Override the default iExec PoCo (Proof-of-Contribution) contract address
 # IEXEC_POCO_ADDRESS=...