Applied Discounts do not match Shopify documentation

[anthlubic]

When adding an applied discount to a draft order or a draft order line item, you can only pass in a single discount. Arrays don't seem to be accepted.

Reference: https://shopify.dev/docs/admin-api/rest/reference/orders/draftorder#create-2020-04

[coveralls]

Coverage remained the same at 100.0% when pulling 86c94624dafdc9313e326032ac6409543725b66b on anthlubic:master into 89ecdd63ceaaafad06b9b57e1a639ff77cd83c3a on MONEI:master.

[lpinca]

Thank you.