Implement `payoutType` in the schema

[onmax]

From the README.md:

• payoutType: The method used to payout the rewards. Possible values are:
  • restake: Rewards are automatically restaked.
  • direct: Rewards are paid directly into the staker's wallet and are not automatically restaked. Requires:
    • payoutAddress: Provide address you will payout from.
    • payoutSchedule: Specify the frequency of payouts using the cron job format. Example: 0 */6 * * * for payouts every 6 hours.
  • none: No rewards will be paid out.
  • custom: Custom payout scheme. Requires:
    • payoutScheme: A description of the custom payout method (e.g., "Pays 50% of rewards every 1st of the month").

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Currently we only have an enum, so this will give us an error.