chore(docs): Updated API Reference (v2) (#9148)

Automated changes by [create-pull-request](https://github.com/peter-evans/create-pull-request) GitHub action

Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

www/apps/api-reference/specs/admin/components/schemas/AdminCustomerGroup.yaml

@@ -1,3 +1,37 @@
 type: object
-description: The group's groups.
+description: The customer group's details.
 x-schemaName: AdminCustomerGroup
+required:
+  - id
+  - name
+  - customers
+  - metadata
+  - created_at
+  - updated_at
+properties:
+  id:
+    type: string
+    title: id
+    description: The customer group's ID.
+  name:
+    type: string
+    title: name
+    description: The customer group's name.
+  customers:
+    type: array
+    description: The customer group's customers.
+    items:
+      $ref: ./BaseCustomer.yaml
+  metadata:
+    type: object
+    description: The customer group's metadata, used to store custom key-value pairs.
+  created_at:
+    type: string
+    format: date-time
+    title: created_at
+    description: The customer group's creation date.
+  updated_at:
+    type: string
+    format: date-time
+    title: updated_at
+    description: The customer group's update date.