Enhancement: Enable attachment of PDFs to accession records

[dannnielle]

Users are currently unable to attach PDF files to accession records. Being able to do so would allow for the centralized tracking of files such as:

• Signed donor agreements and related forms
• Pertinent email correspondence
• File lists that accompanied the donation
• Copyright agreements
• Tax receipts

All of the above are examples of documents historically stored as paper documents in a donation master file.

Running version: AtoM 2.9.1