Scikit-learn user guide (2017) [pdf]
scikit-learn.org
scikit-learn.org
also ironic that it is for free, but adjustments to real world business problems are as expensive as you want (consultants, coders)
>>> model = [insert sklearn class here]
>>> model.fit(trainX, trainY)
>>> model.predict(testX)
The change log has A LOT of value if you are trying to figure out what version you should upgrade to. If you are stuck on an older version, then you need to understand what value you gain by potentially introducing new bugs into your product.
They also credit everybody who has worked on the project, which is super important.
The scope of the PDF is to be the full documentation. If you were used to doing something a certain way, you need to know that things changed.