[JOSS] suggestions for paper

[sappelhoff]

As part of my review for JOSS (openjournals/joss-reviews#4840) I read your paper and have some suggestions. Some I have already tried to integrate in this PR (I tried to be very minimal), the others I write below:

• It'd be good if you could put each sentence on a new line -- this would significantly improve the git diff of the document: Note how currently if I change a single word in the first paragraph, the entire paragraph gets a markup, which is undesirable. The one-row-per-sentence rule can be a good practice for text documents in version control.
• you could add some citations for the claim that Python is increasingly being used. e.g. https://elifesciences.org/labs/f779833b/python-for-the-practicing-neuroscientist-an-online-educational-resource and https://www.frontiersin.org/research-topics/8/python-in-neuroscience
• I suggest using title case for your paper title: Spectral Connectivity: A Python Package for Computing Multitaper Spectral Estimates and Frequency-Domain Brain Connectivity Measures on the CPU and GPU ... at least "Python" must be capitalized