[bill] [banks] [CapDocument] Fix confusion around accepted_doc_types
Some modules did use accepted_document_types instead of accepted_doc_types like defined in weboob.capabilities.bill.CapDocument. Now all modules do use accepted_doc_types.
Some modules did use accepted_document_types instead of accepted_doc_types like defined in weboob.capabilities.bill.CapDocument. Now all modules do use accepted_doc_types.