[2.0.77] previous_recipe could use a little more detail

[Honktown]

furnace.previous_recipe describes a RecipeIDAndQualityIDPair , which "name" is the recipe, but in this case, it's returned as a LuaRecipePrototype. This is a little confusing in my opinion, as I think the first two assumptions on what is contained would be that name is a string, or at least the LuaRecipe of the force of the furnace it came from. Instead it's the LuaRecipePrototype.