Defined the "Service" endpoints for the Open API specification documentation in the library target.

Sources/DiscogsService/openapi.yaml

@@ -143,6 +143,10 @@ info:
 
     If no `Accept` header is supplied, or if the Accept header differs from one of the three previous options, we default to `application/vnd.discogs.v2.discogs+json`.
 
+    # Videos 
+
+    In case an application integrates **YouTube** videos, then third party cookies may be used. Please refer to the [YouTube and Google's cookie policy](https://policies.google.com/technologies/cookies).
+
     # FAQ 
 
     **1) Why am I getting an empty response from the server?**
@@ -238,3 +242,75 @@ tags:
     description: Manage user-created lists.
   - name: Inventory Management
     description: Bulk inventory management via CSV uploads and exports.
+paths:
+  /:
+    get:
+      tags:
+        - Service
+      operationId: service
+      summary: Get service information.
+      description:  Retrieves any available information related to the service.
+      responses: 
+        '200':
+          description: Service information returned successfully.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Service'
+        '500':
+          $ref: '#/components/responses/Unavailable'
+components:
+  schemas:
+    Error:
+      type: object
+      properties:
+        message:
+          type: string
+    Service:
+      type: object
+      description: A type that contains all available service information.
+      properties:
+        hello:
+          description: A welcome message from the service.
+          type: string
+        api_version:
+          description: A current version of the service.
+          type: string
+        documentation_url:
+          description: A URL to the developers' documentation.
+          type: string
+        statistics:
+          type: object
+          description: A type that contains the service's statistics.
+          properties:
+            releases:
+              description: A number of registered releases in the service.
+              type: integer
+            artists:
+              description: A number of registered artists in the service.
+              type: integer
+            labels:
+              description: A number of registered labels in the service.
+              type: integer
+  responses:
+    Unavailable:
+      description: The service is currently unavailable to handle requests.
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+          examples:
+            timeout:
+              value:
+                message: Query time exceeded. Please try a simpler query.
+            malformed:
+              value: 
+                message: An internal server error occurred.
+    Unauthorized:
+      description: Some authentication information is missing or invalid.
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+          example:
+            message: Service not available.