Automatic topic identification from URL

Currently, we are unable to import a lot of book summaries, because we'd need to tag those books with topics they cover. This topic tagging must remain high-quality, otherwise we'll end up with thousands of links under vague categories such as "business" or "personal-development" / "self-help".

However, the topic taxonomy itself cannot be static. While we might not have a topic as granular as "History of Tuberculosis in China", we may need to decide that at some point "Medicine in China" might be worthy of a topic. Some of this discussion is in #14

There's back-and-forth tension between assigning topics/tags to an item using the current taxonomy, and keeping tha taxonomy itself up-to-date by adding/removing topics/tags. So we need a system that can change both the taxonomy and the topic tagging appropriately while removing the manual tagging as a bottleneck. Would love to have more ideas here.