Swamp & Jungle village dig sites for the new books

The new experimental rebalancing of villagers does not need jungle and swamp villages. There is a better way - Archaeology.

The main problem I see with the changes is the discoverability of the biome-specific books, and also finding the biomes may be difficult. So, lets introduce few small structures, so that each biome has some, and cartographers can sell maps where to find these structures.

Jungle and swamps shall get a small "ruined library" structure with a lectern and a mending/unbreaking book as a loot or as a drop from suspicious sand/dirt to provide a clue. The lore shall be that there used to be some outposts, but they are long gone and the nature took over.

The player then can buy a map at any village and it will bring him to the next game content. It would also make sense for the cartographers to have maps of other nearby villages in different biomes - the villagers probably know about each other, so lets give them a way to tell the player. This would also make sense for the wandering trader to sell maps to more distant destinations.