add manual detect method. fixes #23

[jedelson-pagerduty]

I could not figure out how to get the test to pass. It produces this:

TestingLibraryElementError: Unable to find an element by: [data-testid="techdocs-native-shadowroot"]

So I've left the test as skipped.

[johanneswuerbach]

how to get the test to pass

Last time I checked mermaid wasn't able to render inside the test dom, so I fear that this isn't easily testable.

[johanneswuerbach]

Released as v0.6.2, thanks for adding this 🤩