Warning about running example and exceeding Boxmap's Free Tier

[edmundseto]

First off, this is an awesome R package! Thanks!

Yesterday, I was able to successfully follow the example on the walker-data website -- an impressive example of dynamically mapping US county and tracts, nationwide:
https://walker-data.com/mapboxapi/articles/dynamic-maps.html

But, I was surprised this morning to receive a bill from Mapbox for $70 some USD! Apparently running the example generates around 9.8 million km2 of their "1m tileset processing". I read today that you'll only be in the free tier if you keep the max zoom level less than 6 during tileset processing:
https://docs.mapbox.com/help/troubleshooting/manage-tileset-costs/

If you think it'd be helpful, you might want to post a warning with the example, so that casual try'r out'rs like myself, won't be surprised when they get a bill.

Thanks again for great package!

[walkerke]

Thank you! I've been putting these types of warnings throughout the package, I should put one in there as well.