Update bug_report.md (#1836)
Update bug_report.md (#1836)

Update URLs and names to OpenZeppelin and OpenZeppelin Contracts
OpenZeppelin/zeppelin-solidity,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/zeppelin-solidity,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/zep-solidity,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/zep-solidity