refactor: streamline example 1

1_single_core_job/README.md

1_single_core_job/single_core_task.py

1_single_job_step/README.md

1_single_job_step/parallel_task.py

1_single_job_step/sequential_task.py

1_single_job_step/single_job_step_parallel.sh

1_single_job_step/single_job_step_sequential.sh