New snack + potato chips recipe

This is a small PR to add a couple of food-related things.

First is a recipe for potato chips. Compared to the baked potato recipe, it needs more ingredients (salt) and tools (a knife), but the end product won't go bad.

Second is popcorn. It can be found pre-cooked (like the bags you find in supermarkets and snack aisles), or as a raw kernel (which can then be cooked later on). It's about on par with potato chips, and is found in some of the same places.