Update test to reflect 2.2 and axe

[mgifford]

Purple a11y leverages axe. Axe now has some elements of WCAG 2.2 in it.

So this text can change:

Only a subset of WCAG 2.1 (Conformance Level A & AA) Success Criteria can be automatically checked so manual testing is still required.

It is also worth adding what version of axe you are using on this page. It would fit nicely under "Purple A11y Version 0.9.41" in the left column.