Introduced the --copy-parallel flag to enable concurrent copying of Docker images to multiple hosts. Updated the README with usage instructions and details about the new option. Refactored the script to support both serial and parallel copy modes for improved efficiency.
Updated build-and-copy.sh to support copying Docker images to multiple hosts using the new -c/--copy-to flag, which accepts space- or comma-separated host lists. The old --copy-to-host flag is retained as an alias for backward compatibility, and -h is now used for help. The README was updated to document these changes and provide new usage examples.
