[MRG] DOC Add link of kernal approx to svm user guide (#23535)
[MRG] DOC Add link of kernal approx to svm user guide (#23535)

* Add link of kernal approx to svm user guide

* Update doc/modules/svm.rst

Co-authored-by: Gael Varoquaux <b682965d6a8eba053068a9d9edbcf3855b7d8bc5@normalesup.org>

Co-authored-by: Gael Varoquaux <b682965d6a8eba053068a9d9edbcf3855b7d8bc5@normalesup.org>
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