[DOC] Update Partitional clustering notebook (#2483)

* Update Partitional clustering notebook

I have addressed issue #1805 by updating the partitional_clustering notebook to include all the supported distance metrics.

* Fix issue with additional </li> tag

* Fix issue with additional </li> tag

* Removed <!-- --> tag present earlier

Investigated issue with additional </li> tag by using a comment tag. Reverted the comment tag as it is unnecessary.