Prompt: Only show last 2 directories

<img width="413" alt="Image" src="https://github.com/user-attachments/assets/feeecc8a-fbbe-41ff-a3e3-50de4a75f964" />

The first is `shell`, the second is `zsh`.

I like to setup my bash and zsh to only show the last two directories, to save horizontal space.