Describe the problem you'd like to have solved

"IssuedAt" (IAT) claim verification has been made optional following the close of issue-254. However "acceptIssuedAt" documentation is not updated and confusing.

Describe the ideal solution

If the documentation of "acceptIssuedAt" function can be updated to state that IAT claim verification is by default but optional, it will make it clear and avoid confusion. I can provide a PR to update it.

Alternatives and current work-arounds

Additional information, if any