Update 'Imaging applications in healthcare'

[SystemsResearch]

The "Imaging applications in healthcare" section mentions mammography.
There has been a lot of work in that space, for instance through the Digital Mammography DREAM Challenge.

The overview paper for that challenge was published in JAMA Network Open in March.

The section could be updated to discuss some of the approaches taken in the challenge, as well as the overall implications of the results.