refactor: streamline example 3

3_job_array/README.md

3_job_array/config.txt

3_job_array/data/parameters_first_job.txt

3_job_array/data/parameters_second_job.txt

3_job_array/data/parameters_third_job.txt

3_job_array/job_array.sh

3_job_array/job_array_task copy.py

3_job_array/job_array_task.py

data/data_1.txt

data/data_2.txt

data/data_3.txt

data/data_4.txt