Clarifies non-existing attributte (`aria-not-checked`)

[daniel-montalvo]

<< Describe the changes >>

Closes issue(s):

• closes #XXX (ADD ISSUE NUMBER HERE)

Need for Call for Review: << choose one of the following and remove the rest >> << check Process Document on Call for Review >> This can be merged with 1 approval << choose reason: editorial changes to website/test code, adding new contributor, other (explain). >>

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[daniel-montalvo]

Closing as per https://github.com/act-rules/act-rules.github.io/pull/2005#discussion_r1072359474