Both Documents and Contacts work in the same way, where once you create/edit a contact or document and assign a building to it - it will show up inside the building info. 

What to know;

• You can assign a contact or document to show up inside the building view for one or more properties.
• If you create a contact or document inside the building view/level it will auto be assigned to that building.
• You can always edit/remove any contacts or documents assigned to a building.
• You can only assign a contact or document to a building that has already been created in the ERP plan.