Paper submission

[olivierlabayle]

TODO:

• [ ] Address: https://github.com/olivierlabayle/TMLE.jl/issues/49
• [ ] Update docstrings
• [ ] Update documentation
• [ ] Write paper
• [ ] Submit

For reference: https://joss.readthedocs.io/en/latest/submitting.html#submitting-your-paper

and

https://github.com/alan-turing-institute/MLJ.jl/tree/dev/paper