add screenshot to README.md

Author: BenWibking

README.md

@@ -13,7 +13,9 @@ $ ./launch_amrvis_browser.sh
 ```
 Then open http://localhost:8080/ and copy-and-paste the autogenerated password printed to the terminal.
 
-An `xterm` window should appear. Then you can type either `amrvis2d` or `amrvis3d` to launch Amrvis.
+An `xterm` window should appear. Then you can type either `amrvis2d` or `amrvis3d` to launch Amrvis:
+
+<img width="1318" alt="Screenshot 2025-05-25 at 2 00 36 PM" src="https://github.com/user-attachments/assets/00fe557b-8c4d-4412-a6cd-2c9f9d6f4f26" />
 
 **Caveat: The container hangs when clicking on the orthonormal viewports in Amrvis. No workaround is currently known, so this feature remains on the `xpra` branch, rather than on `main`.**