Added guide for downloading data from Box to campus clusters.

[charwich]

Added user guide for downloading data from Box to campus clusters, in response to increasing requests to migrate projects.

[Guangzhen-Jin]

1. ````markdown format is not needed. It will be rendered into the below. You can start with the front matter.
2. Please add link(s) on which page will use the new page. Otherwise it will become an orphan page that no one can find.
3. Make sure to run mkdocs serve locally and check if the page can be rendered correctly, following our staff notes.