images/README.md

These images are freely-usable ones from Unsplash.

• https://unsplash.com/photos/rDEOVtE7vOs
• https://unsplash.com/photos/et_78QkMMQs
• https://unsplash.com/photos/ILip77SbmOE
• https://unsplash.com/photos/95UF6LXe-Lo