text: Title: [Examples] Fix docstring of to_screenshot.py and export_figure.py
  Body: ## 🧰 Task
  As identified in https://github.com/napari/napari/pull/7319 the docstrings (which end up being the copy in the napari.org gallery example) are not correct for the screenshot and export_figure examples. See:
  <img width="891" alt="image" src="https://github.com/user-attachments/assets/12e32f4f-bd04-46e7-af68-2427a7a2c806">
  
  Looks like it's placeholder text that wasn't updated.
  to_screenshot:
  https://github.com/napari/napari/blob/d9fd074601d4bac7ff8ff6f0db1338d3301726e5/examples/to_screenshot.py#L1-L10
  
  export_figure
  https://github.com/napari/napari/blob/d9fd074601d4bac7ff8ff6f0db1338d3301726e5/examples/export_figure.py#L1-L10