Demonstrates the following:
- Accessing a list of National Parks via an API call
- Displaying the parks on a map using Leaflet
MAP_KEY can be acquired here: https://www.mapbox.com/studio/account/tokens/
NPS_API_KEY can be acquired here: https://www.nps.gov/subjects/developer/get-started.htm
MAPBOX_ACCESS_TOKEN=
NPS_API_KEY=