Improve code comments in ERC1967._upgradeToAndCallSecure
Improve code comments in ERC1967._upgradeToAndCallSecure

(cherry picked from commit 2e6ef74593157333a7135405f5b47bbf8ebd2e88)

OpenZeppelin/zeppelin-solidity,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/zeppelin-solidity,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/openzeppelin-contracts