Add sources to disease pages

100% - although we are still working on other content, I can go through what we have again first in order to add such documentation (more than likely in a Wikipedia reference style where we will indent with numbers, that will correlate to references at the bottom of each page/article).

This will take some time since I need to dig up the studies/reference we used prior, but I'll keep you posted once we have everything marked up that we currently have now. Additionally, we'll be adding photos to those articles and pages as well in order to decrease the blocks of text, and add insights that many would find helpful in being able to compare/contrast.