DOC - Reorganizing the "Development" section in the website top bar

[rcap107]

A general comment:
in the "Development" section of the website, there are subsections including the one you want to add and "Contributing to skrub". "Contributing to skrub" is then also a section in the drop-down of "More". We might want to add an issue to clear this up.

Originally posted by @jovan-stojanovic in #1578 (review)

[divakaivan]

Is the preferred option to have "Contributing to skrub" as part of the "Development" page rather than on its own (in the More dropdown)? Also would it make sense to rename this to just "Contributing"? Since the context is already within the skrub repo, "Contributing to skrub" might be a bit redundant.

[rcap107]

I think we can start by removing "Contributing to skrub" from the drop down menu, since it's already present in the "Development" page.

Something I would also like to do is rework the "Contributing to skrub" page so that the outline has less nesting, which is similar to what I am trying to do in #1574. This is a bit more complex, so for later.

[rcap107]

#991 should also be addressed

[rcap107]

To remove the "contributing" section from the bar, it is sufficient to edit doc/index.rst to remove CONTRIBUTING.

The documentation of the table report should be cleaned up (if needed) and moved to the doc folder so that it can be called from the development.rst TOC.

We might also consider reformatting a bit the Development outline if needed.