docs: misleading outdated comment at EIP712Upgradeable

[DefiCake]

The EIP712Upgradeable contract seems to have misleading / outdated documentation in the comments.

💻 Environment

Latest (5.2.0)

📝 Details

At https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/blob/master/contracts/utils/cryptography/EIP712Upgradeable.sol

/**
 ...
 * NOTE: In the upgradeable version of this contract, the cached values will correspond to the address, and the domain
 * separator of the implementation contract. This will cause the {_domainSeparatorV4} function to always rebuild the
 * separator from the immutable values, which is cheaper than accessing a cached version in cold storage.
 */

There are no use of immutables or constants in the contract. This note should go away.

🔢 Code to reproduce bug

Not relevant

[Amxx]

Hello @DefiCake

https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/blob/master/contracts/utils/cryptography/EIP712Upgradeable.sol is the upgradeable version. Its true that in the transpilation process, the cache is removed completelly. Would it make more sens to you if we replaced it with

* NOTE: The upgradeable version of this contract does not use an immutable cache and recomputes the domain separator
* each time {_domainSeparatorV4} is called. That is cheaper than accessing a cached version in cold storage.