Correct the deploy account page and provide more ways to deploy accounts using UDC

[odednaor]

In the deploying new accounts page: https://docs.starknet.io/documentation/architecture_and_concepts/Accounts/deploying_new_accounts/#validate_deploy

When using the deploy_account transaction, the deployed contract must have a __validate_deploy__ entrypoint. Currently this is mentioned as optional.

One can also deploy an account using the deploy syscall. There is a convenient option to use this syscall using the Universal Deployer Contract (UDC) by OpenZeppelin.

[stoobie]

@odednaor Does #1011 cover this?

[stoobie]

Addressed by #1163.