Document how to find data files

[rwegener2]

Many of the lessons and practice sheets use data files that are stored in the GitHub repository. They can be downloaded from GitHub, but it isn't obvious how to do that since there isn't any documentation. It would be great to think through a clean way to distribute these files and make that more obvious.

Brainstorming

• Move all the data file to a single data folder and document on the website that is the folder to download data from
• Add a link to the raw file on GitHub anywhere in the website where the file is used
• Only use data accessible from earthaccess and have all notebooks download data on demand