[Topic] Frontend checks for web accessibility

[rianrietveld]

URL: https://wpaccessibility.org/docs/testing/code/
Code: https://github.com/wpaccessibility/wp-a11y-docs/blob/main/docs/testing/code/index.md

Please read How to contribute before you start.

Tasks

This content should be reviewed, restructured and expanded.
The links need to be checked and updated.
Some info/resources can be moved to the topics (and linked to) Standards and best practice.
Some topics are not frontend related.