This PR accomplishes 2 things:
1. You can now add images to the rich text post of the example and see those images show up in the app. This is a good jumping off point for people who are learning how to customize the rich text renderers by adding custom components to the mapper.
2. Updating the README pictures to have a more up-to-date UI in the screenshots.
## Feature
- [x] Documentation added
## Documentation / Examples
- [x] Make sure the linting passes by running `yarn lint`