Explain how Scour works#104

Similar to #95, it would be useful to have a page explaining how Scour works and how it ranks posts.

This should include:

• Where the feeds come from (they are added by users)
• What’s the difference between adding feeds yourself and scouring everything
• How it uses interests to rank items
• How it handles when you have multiple interests
• How loves/likes/dislikes are used
• How interest and feed recommendations are generated

And maybe other things?

Thanks to Andrew Doran for this suggestion

Done! There is now a comprehensive docs section that explains how Scour works and how to use it, along with guides for RSS users and readers of Hacker News, Reddit, arXiv, and Substack.

https://scour.ing/docs

Please let me know if you have any feedback on these!