add comparison with other libraries for peak detection

[LegrandNico]

As the added value of the package is to facilitate the use of machine learning and deep learning methods to analyse ECG signal, it would be useful to see how this relate to other methods, especially methods that are simpler. I would suggest a comparison with the peak detection algorithms provided by Neurokit2 and SleepECG.

This issue is related to the review of the package for JOSS (see here).

[devnums]

Thank you for your suggestion. I have edited the paper, please take a look at it here and let me know if that's what you mean.