[guide] DataHUB: uploading / downloading files (without git)

[Brilator]

Create guides to up/download files and directories; i.e. interact with DataHUB's file tree

Rationale:

• show how to collaborate on data with people who do not frequently use ARC, ARC commander
• use-case: core facility that uses ARC, customers who just want to upload their metadata (samples) and download the assayed data