Add JOSS paper source

[ortk95]

Pull request checklist

• [ ] Add a clear description of the change
• [ ] Add any new tests needed
• [ ] Run spell check on new text visible to user (documentation, GUI etc.)
• [ ] Check any changes to requirements.txt are reflected in setup.py
• [ ] Check code passes CI checks (run run_ci.sh or check GitHub Actions)

See CONTRIBUTING.md for more details.

[coveralls]

Pull Request Test Coverage Report for Build 6471387686

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.002%) to 99.498%

---

Totals
Change from base Build 6471281763:	-0.002%
Covered Lines:	2751
Relevant Lines:	2765

---

💛 - Coveralls