Hello Joachim,
Please take a look at this article for a brief overview.
Transformers includes fairly extensive documentation built into the plugin itself. For each transformer you can click on the ℹ icon to the right of the menu and learn more about it.
Choosy has a big button (shown below) that takes you to a web page with documentation.

Hope that helps,
Bill
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This reply was modified 3 years, 1 month ago by
Bill Finzer.
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This reply was modified 3 years, 1 month ago by
Bill Finzer.