fix(specs): value/price clarifications in the Insights API (#5154)

Author: kai687

specs/insights/common/schemas/EventAttributes.yml

@@ -97,7 +97,7 @@ positions:
   example: [1, 2, 5]
 
 price:
-  description: Total price of a product, including any discounts, in units of `currency`.
+  description: Final price of a single product, including any discounts, in units of `currency`.
   oneOf:
     - type: number
       format: double
@@ -179,7 +179,9 @@ currency:
   example: EUR
 
 value:
-  description: Total monetary value of this event in units of `currency`.
+  description: |
+    Total monetary value of this event in units of `currency`.
+    This should be equal to the sum of `price` times `quantity`.
   oneOf:
     - type: number
       format: double