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

docs/api/store/paths/variants_{variant_id}.yaml

@@ -0,0 +1,42 @@
+get:
+  operationId: GetVariantsVariant
+  summary: Retrieve a Product Variant
+  description: Retrieves a Product Variant by id
+  parameters:
+    - in: path
+      name: variant_id
+      required: true
+      description: The id of the Product Variant.
+      schema:
+        type: string
+    - in: query
+      name: cart_id
+      description: The id of the Cart to set prices based on.
+      schema:
+        type: string
+    - in: query
+      name: region_id
+      description: The id of the Region to set prices based on.
+      schema:
+        type: string
+    - in: query
+      name: currency_code
+      style: form
+      explode: false
+      description: The 3 character ISO currency code to set prices based on.
+      schema:
+        type: string
+        externalDocs:
+          url: https://en.wikipedia.org/wiki/ISO_4217#Active_codes
+          description: See a list of codes.
+  tags:
+    - Product Variant
+  responses:
+    '200':
+      description: OK
+      content:
+        application/json:
+          schema:
+            properties:
+              variant:
+                $ref: ../components/schemas/product_variant.yaml