Find a solution to update/provide the library/catalog in a pure P2P manner

The catalog of content (not the content themself) is currently available at http://www.kiwix.org/library.xml.

That means if for any reason this file is not available anymore from Kiwix, none of the Kiwix client can get updates.

This is a pretty dangerous single point of failure which should be fixed.

This ticket is about proposing a method allowing:
* Kiwix team to update the catalog with new content
* Allowing Kiwix SW to download the new versions of the catalog using a decentralized P2P solution

https://sourceforge.net/p/kiwix/feature-requests/830/

Start by reviewing the current catalog at http://www.kiwix.org/library.xml and the linked SourceForge feature request. Define how the Kiwix team would publish catalog updates and how Kiwix software would retrieve them without relying on that single endpoint. Done means a concrete, agreed decentralized update proposal.

Written by the indexing model from the issue text.