scanner docs

[cycomachead]

I've added some basic docs for some more exam logistics:

• How to print to the copiers in Soda via USB (with screenshots)
• A new "Exam Scanning" page with details on the scan-exams command
  • There is a large and fast scanner currently in my office that will eventually need to be moved to a shared location in the Gateway.
  • The scan-exams command is a batch scanning tool that produces compressed, timestamped PDFs with a specific filename convention. It also has features like automatic semester detection and batch numbering. (It's really just a bash script adapted by Claude...)

• Add URL to readme
• Add scanner docs for the scanner in my office