The first killer app of AI for businesses, it appears, is a simple thing: to be able to find information in the morass of files, folders, attachments, incompatible enterprise software apps, and everything else that constitutes modern knowledge work. Notion, which aims to replace most of those things in a single tool, is launching a feature it thinks can help. It’s called Q&A, and CEO Ivan Zhao describes it to me as essentially an all-knowing AI executive assistant that knows everything…