added api docs

interface/models/common/money.yaml

@@ -0,0 +1,16 @@
+components:
+  schemas:
+    Money:
+      type: object
+      additionalProperties: false
+      required:
+        - amount
+        - currency
+      properties:
+        amount:
+          type: string
+          description: Decimal string amount.
+          example: '125.50'
+        currency:
+          type: string
+          example: USD