Add support for class attribute in links

[Shulammite-Aso]

Fixes #512

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[Shulammite-Aso]

@jywarren wondering why this check is not completed yet, is it normal?
Been this way for a week or more 🤔 with some of the other PR's too as I can see.

[cypherean]

Try rebasing it?

[Shulammite-Aso]

Try rebasing it?

will do this now

[jywarren]

Great! 🎉 🎉