Improve the index pages pagination by implementing the new option from Pelican 4.6

[silverhook]

Pelican 4.6 introduced a more SEO-friendly, and above all, more predictable pagination of index pages. It would be nice if Elegant would enable that by default.

Pelican 4.6 is now available. Thanks to Tom Adler’s contribution, this release contains a new feature that allows for more SEO-friendly index pages, whereby /page-1/ contains the oldest articles, with newer articles placed on /page-2/, /page-3/, etc. That way, the names of the previous article index pages do not change every time a new index page is generated. Cool URLs don’t change!

More info and instructions on what needs to be done in the theme to apply it:
https://blog.getpelican.com/pelican-4.6-released.html