docs: reorganise the readme (#2743)
docs: reorganise the readme (#2743)

* docs: reorganise the readme

One of the most common questions people have is what rules axe-core has, and how they map to WCAG. I hope that by being more explicit in the readme, and putting this section higher up we can limit how often this question is asked.

* Update README.md

* Update README.md
dequelabs/axe-core,dequelabs/axe-core,dequelabs/axe-core,dequelabs/axe-core