Update receiveing and checkin schemas

the drafts of the receiving and check-in schemas need to be updated now that we have a better idea of what needs to look like.

receiving_collection FIelds:

• (integer) total_records – The number of receiving records
• (array) to_be_received
  • (string) po_line_id – UUID of po_line
  • (integer) received – Number of items received; Should align with the length of the items array
  • (array) items
    • (string) barcode – The barcode assigned to the piece
    • (string) comments – Free form notes pertaining to this piece
    • (string) caption – Caption (enumeration) of this piece
    • (string) location_id – UUID of location

checkin_collection Fields:

• (integer) total_records* – The number of receiving records
• (array) to_be_checked_in
  • (string) po_line_id* – UUID of po_line
  • (integer) received – Number of items received; Should align with the length of the items array
  • (array) pieces
    • (string) barcode – The barcode assigned to the piece
    • (string) comments – Free form notes pertaining to this piece
    • (string) caption* – Caption (enumeration) of this piece
    • (boolean) create_item – Whether or not to create an item record for this piece
    • (boolean) supplement – Whether or not this is supplementary material
    • (string) location_id* – UUID of location
    • (string) material_type_id – UUID of materialType
    • (string) product_id – Product ID
    • (string) product_id_type – UUID of product id type (ISBN/etc.)
    • (string) accession_number – ?
    • (string) item_description – Description to be associated with the item record
    • (string) electronic_book_plate – ?

* = required

Acceptance Criteria:

• both schemas are updated
• examples are updated and valid