Change rEFindPULS configuration file due to OpenCore change.

This is a modification of the following article posted earlier.
OpenCore dual Boot issue(with windows etc)

OpenCore 0.6.6 Build659c51b9d06f13bd3570adf30add5f6897358ab6 Bootstrap is gone.
Change refind.conf as follows.

    loader \EFI\OC\Bootstrap\Bootstrap.efi
change to
    loader \EFI\OC\OpenCore.efi