In the OpenZeppelin
ERC20.sol contract you can find
* We have followed general OpenZeppelin guidelines: functions revert instead * of returning `false` on failure. This behavior is nonetheless conventional * and does not conflict with the expectations of ERC20 applications.
I searched a hard reference to these guidelines and found https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/GUIDELINES.md but there's no mention of revert vs return. Is there anything else?