docs: add WCAG 2.2 and level AAA

README.md

@@ -14,14 +14,12 @@ Axe is an accessibility testing engine for websites and other HTML-based user in
 
 ## The Accessibility Rules
 
-Axe-core has different types of rules, for WCAG 2.0 and 2.1 on level A and AA, as well as a number of best practices that help you identify common accessibility practices like ensuring every page has an `h1` heading, and to help you avoid "gotchas" in ARIA like where an ARIA attribute you used will get ignored.
+Axe-core has different types of rules, for WCAG 2.0, 2.1, 2.2 on level A, AA and AAA as well as a number of best practices that help you identify common accessibility practices like ensuring every page has an `h1` heading, and to help you avoid "gotchas" in ARIA like where an ARIA attribute you used will get ignored. The complete list of rules, grouped WCAG level and best practice, can found in [doc/rule-descriptions.md](./doc/rule-descriptions.md).
 
 With axe-core, you can find **on average 57% of WCAG issues automatically**. Additionally, axe-core will return elements as "incomplete" where axe-core could not be certain, and manual review is needed.
 
 To catch bugs earlier in the development cycle we recommend using the [axe-linter vscode extension](https://marketplace.visualstudio.com/items?itemName=deque-systems.vscode-axe-linter). To improve test coverage even further we recommend the [intelligent guided tests](https://www.youtube.com/watch?v=AtsX0dPCG_4&feature=youtu.be&ab_channel=DequeSystems) in the [axe Extension](https://www.deque.com/axe/browser-extensions/).
 
-The complete list of rules, grouped WCAG level and best practice, can found in [doc/rule-descriptions.md](./doc/rule-descriptions.md).
-
 ## Getting started
 
 First download the package: