chore(docs): Refactor API Reference (#1883)

docs/api/admin/paths/discounts_code_{code}.yaml

@@ -0,0 +1,33 @@
+get:
+  operationId: GetDiscountsDiscountCode
+  summary: Retrieve a Discount by code
+  description: Retrieves a Discount by its discount code
+  x-authenticated: true
+  parameters:
+    - in: path
+      name: code
+      required: true
+      description: The code of the Discount
+      schema:
+        type: string
+    - in: query
+      name: expand
+      description: Comma separated list of relations to include in the results.
+      schema:
+        type: string
+    - in: query
+      name: fields
+      description: Comma separated list of fields to include in the results.
+      schema:
+        type: string
+  tags:
+    - Discount
+  responses:
+    '200':
+      description: OK
+      content:
+        application/json:
+          schema:
+            properties:
+              discount:
+                $ref: ../components/schemas/discount.yaml