Refresh the "pc-bios/README" file with edk2 and OpenSSL release info,
matching the edk2-stable202008 firmware images added in the previous
patch.

Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugs.launchpad.net/qemu/+bug/1852196


Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <e967b4d5-bcc2-3846-0ad6-9e8f4d2f9115@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>