Update details about running llama in Termux on Android mobile

[wanix1988]

The original README.md does not contain details for the Android using Termux. I will update the corresponding details with a result picture.

[sqzhang-jeremy]

Run Llama2-7B in Google Pixel 8 Pro.

[github-actions]

This issue was closed because it has been inactive for 14 days since being marked as stale.