Add book recommendations

[nbeloglazov]

At the bottom of a book page we should add "also checkout the following books". At the start we can suggest books from the same genre or same author. In future, if we add ability for users to like books, we can recommend books based on what other users liked.

[nbeloglazov]

One of potential solutions - https://www.algolia.com/products/recommendations We are already using Algolia for search.