post https://api.okoora.com/api/v1.0/Payer/UploadFiles
Uploading essential files to the payer. The list of which, and how many files are needed to be uploaded is found on https://okoorapi.readme.io/reference/payer-payment-reasons-documents-needed. Each upload should be for a specific document type.
Invoice = 1
InvestmentAgreement = 2
AccountManagementCertificate = 3
TaxAuthorityApproval = 4