I don't have any opinion on removing the part of the sentence. It will be helpful if you can list the scenarios where you feel document is lacking so that it can be improved. One area I have found to be little tricky is patching the correct object during testing which has a section and needs some understanding of Python's import mechanism. The other was about setting return value properly for nested attributes.

Mock has a lot of features and has a wide range of API so listing places where you feel some of the things are not clear will help in improving them.