add subfig/minipage example in joss sample paper?

[danielskatz]

Should we update the example paper in the docs for this?

The origin of the error is that pandoc (the tool we use to produce pdf and metadata JATS files) can't handle subfigures like the fig1 and 2 in the paper.md. There are two options to solve this: One solution is to combine both panels into a single image. Another solution is to include the jats code into the paper.md file so pandoc can use it.
I've opened a pull request that should solve the problem using the second option.

Originally posted by @xuanxu in openjournals/joss-reviews#4622 (comment)