Additional steps for attestation encryption contract

For the contract with attestation encryption, perform the following additional steps:

1. Set the attestation public key value by running the following command:

   export attestation_public_key=$(cat attestation_public_key.pub | base64 -w0)

2. Add the attestation public key to user-data.yaml by running the following command:

   echo "attestationPublicKey: ${attestation_public_key}" >> user-data.yaml

3. Continue with Step 3 from Creating a signed contract section