Add UML diagram for documentation purposes

[jonathanpv]

I was pretty taken aback at how complex uploading files actually is so I made it into a uml diagram to help understand it better

Seems like client based uploading including larger files is actually fairly difficult

This doesn't even include logic for accessing the files after they've been uploaded haha

[anuveyatsu]

Great @jonathanpv 👏🏼 I missed this issue so only seeing it now. I think it would be great if we had editable version of the diagram so that other people could improve/fix it if any issues. Generally, we'd use mermaid diagrams and open a pull request with the diagram included in the README of this repo.