Get network name by extracting it from deployment.yml

ops/deployments-from-scratch.md

@@ -144,13 +144,12 @@
   * On the deployment VM, set the following variables:
 
     ```bash
-    # Switch to `/srv/op-sepolia` directory on the virtual machine
     cd /srv/op-sepolia
 
     L1_RPC=http://host.docker.internal:8545
     L2_RPC=http://host.docker.internal:9545
 
-    NETWORK=<the network name found above>
+    NETWORK=$(grep 'cluster-id' optimism-deployment/deployment.yml | sed 's/cluster-id: //')_default
 
     DEPLOYMENT_CONTEXT=11155111
     ACCOUNT=<admin-account-address>