Add Cave Area with descriptions and implementation

@@ -105,3 +105,26 @@ mountain_peak.add_exit("south", rocky_path)

# Connect Forest Entrance to Mountain Base

forest_entrance.add_exit("up", mountain_base)

```

## Cave Area

- **Cave Mouth**: A dark opening in the side of the mountain. A cool breeze blows from within. Exits: north (Dark Tunnel), south (Mountain Base).

- **Dark Tunnel**: The walls are damp and the path is narrow. You hear the sound of dripping water. Exits: north (Underground Lake), south (Cave Mouth).

- **Underground Lake**: A vast subterranean lake with glowing fungus on the walls. Exits: south (Dark Tunnel).

## Cave Area Implementation

```python

cave_mouth = Room("Cave Mouth", "A dark opening in the side of the mountain. A cool breeze blows from within.")

dark_tunnel = Room("Dark Tunnel", "The walls are damp and the path is narrow. You hear the sound of dripping water.")

underground_lake = Room("Underground Lake", "A vast subterranean lake with glowing fungus on the walls.")

cave_mouth.add_exit("north", dark_tunnel)

cave_mouth.add_exit("south", mountain_base)

dark_tunnel.add_exit("north", underground_lake)

dark_tunnel.add_exit("south", cave_mouth)

underground_lake.add_exit("south", dark_tunnel)

# Connect Mountain Base to Cave Mouth

mountain_base.add_exit("east", cave_mouth)

```