URL

https://ionicframework.com/docs/react/your-first-app#photo-gallery-

Issue Description

Similarly to #2082, but for React, the tutorial should show the complete code blocks so that it is easy to copy and paste.
Currently, the code blocks only display what needs to be added or changed, but they do not indicate where the code should be placed or provide any additional context. For more experienced Ionic devs, this may be fine, but for those starting with Ionic, I think this additional context would go a long way in making this tutorial more approachable.