Often, multiple license files are picked up when scanning a source tree, and some of these will not be able to be mapped to a known license - this is particularly true when creating recipes for node.js modules. These unknown licenses are squashed down to a single "Unknown" entry in the LICENSE value within the created recipe, which isn't very helpful if you want to go and find just those. We should add an explicit comment within the recipe about which license files couldn't be mapped to a LICENSE entry.