Update Views documentation for D8

Aka dropped and rewritten from scrotch.

This area has never been considered as proper source of views documentation.

What is with the Advanced help? Point 4 of the to do list "Before the first Drupal 8 release candidate" mentions moving the Views advanced help to drupal.org:

Move the old advanced help documentation onto Drupal.org and update it for the new architecture.#1892470: Update Views documentation for D8

So step one of moving was done, (remove) step two not yet(add new documentation on drupal.org) :(

I had a look at the advanced help and the material doesnt seem immediately ready to be put in drupal.org as it is. It contains a lot of references to Drupal 6 versions of Views.

How up-to-date do you think the advanced help texts of Views are?

They are basically at mostly at Drupal 6 version of views, some of them got updates, but well it feels like having at least some documentation idea would be helpful.

It seems the documentation has been updated for Drupal 8: https://www.drupal.org/docs/8/core/modules/views.