Update documentation

[TimotheeMathieu]

Update of documentation

• make a cluster module User-Guide section
• change examples to separate basic examples from specialised module examples
• update KMedoids doc: add pam and an example of face recognition article (for which KMedoids is very suitable)

I changed the structure of the doc a bit so if you don't like it, tell me and I will make the changes.

[rth]

There are some changes here from #73 so we would need to merge that one first.

But otherwise thanks a lot for improving the documentation, it really needs it.

BTW, the way to avoid such issue with branchs is to always come back master, syncing with upstream and creating a branch from there for other PRs,

git checkout master
git fetch upstream
git rebase upstream/master
git checkout -b new-feature

where upstream was defined as,

git remote add upstream [email protected]:scikit-learn-contrib/scikit-learn-extra.git

(or https://github.com/scikit-learn-contrib/scikit-learn-extra.git if you use HTTP authentication).

[TimotheeMathieu]

Ok thanks. Yes I was wondering what's up with all those commits.

[rth]

Thanks @TimotheeMathieu ! It looks like a nice improvement.

The on case in test_kmedoid_results failed but I see it also did on master. I think we need to fix the random state there.