Describe the issue linked to the documentation

sklearn.utils.deprecate is updating the docstring within _update_doc()
This causes the numpydocs to fail during the test with the error:

GL09: Deprecation warning should precede extended summary

After discussing with @glemaitre and @ogrisel : the _update_doc() should be removed from sklearn.utils.deprecate ensuring that the appropriate depracation message appears in all the docstrings using the @deprecated decorator at the moment.

Suggest a potential alternative/fix

No response