short technical explanation about fuzzy hashes

[zeroheure]

Useful to learn more.
Comes from SSDEEP documentation https://ssdeep-project.github.io/ssdeep/index.html

[TonyGravagno]

@zeroheure A lot of changes have been made to this page and more are coming. What do you think of the latest version? While it doesn't reference CTPH or go deep into the details what a fuzzy hash actually is, does the content now do a better job of allowing the reader to understand what this is about?

Perhaps it would be better to reference the abstract from which the ssdeep project originates: https://www.sciencedirect.com/science/article/pii/S1742287606000764?via%3Dihub ? That also eliminates possible confusion about whether or not that ssdeep project is in any way related to Rspamd - it's not.

In general, I'm taking a shot at improving the documentation for Rspamd users. This first round of updates bloats the pages with more info that some people would want. That's intentional to start, just so all related content is in one place. In a next phase there might be an area dedicated to pure, concise how-to info, and another dedicated to understanding how and why Rspamd implements the various concepts.

Thoughts?