[Wuerstchen] fix compel usage (#4999)
* fix compel usage
* minor changes in documentation
* fix tests
* fix more
* fix more
* typos
* fix tests
* formatting
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Co-authored-by: Dominic Rampas <d6582533@gmail.com>
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
