Add paragraph about manual discount deletion in combination with vouc…

…hers

docs/developer/discounts/manual-discounts.mdx

@@ -355,3 +355,10 @@ The rest of the discount, **$13** was applied to the subtotal and next propagate
 its price was discounted by $10 (100 / 130 * 13).
 
 For more complex cases, please check [Examples](developer/discounts/examples.mdx) section.
+
+
+### Manual discounts with vouchers
+
+Manual discounts take precedence and override vouchers. However, it doesn't mean the voucher is completely disconnected from an order. 
+Ie. when the manual discount is deleted, the voucher code associated with the order is evaluated again. 
+If the voucher has a [usage limit](developer/discounts/vouchers#usage-limits) and a manual discount overrides it, the usage is not released.