contract/contract_sale_invoicing/readme/USAGE.md

To use this module, you need to:

1. Go to Invoicing > Customers > Customers Contracts and select or create a new contract.
2. Check Generate recurring invoices automatically.
3. Mark the check "Invoice Pending Sales Orders".
4. On each invoicing, system will check if there's any pending sales orders with same analyitic account and will append the lines to the invoice being generated.