Expose event parameter

[blaumeise20]

This PR adds the optional parameter event to all methods provided in options. This allows you to access the event target.

[sindresorhus]

What's the use-case?

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You also need to update the readme and index.d.ts doc comments.

[blaumeise20]

I fixed the documentation now.

The use case is very simple: You want to show different actions depending on the element you right-click on. Do you understand? For example: you click on an element in the sidebar and you get a different menu than clicking on an element in the main view.