docs: in the YAML schema, fix the link to product_quality.yaml

[jforget]

The product.yaml file uses the following components, among others:

allOf:
  - $ref: "../api.yml#/components/schemas/Product-Data-Quality"
  - $ref: "../api.yml#/components/schemas/Product-Knowledge-Panels"

The api.yml file defines the following components (among others):

components:
  schemas:
    "Product-Quality":
      $ref: ./schemas/product_quality.yaml
    "Product-Data-Quality":
      $ref: ./schemas/product_knowledge_panels.yaml
    "Product-Knowledge-Panels":
      $ref: ./schemas/product_knowledge_panels.yaml

It seems there was a copy-paste-fail error.

There are two possible fixes:

(1) product.yaml should refer to Product-Quality instead of Product-Data-Quality
and in api.yml the component Product-Data-Quality should be removed

(2) in api.yml, the component Product-Data-Quality should point to file product_quality.yaml