DOC: Added an API contract for arts/:userId (#199)

* added documentation for arts/:userId

* fixed one error code

arts/README.md

@@ -0,0 +1,62 @@
+# ARTS
+
+| Method | Route                                           | Description                                                    |
+| ------ | ----------------------------------------------- | -------------------------------------------------------------- |
+| GET    | [/arts/:userId](#get---arts)                    | It will fetch you the user arts based on id.                   |
+
+## Art Object
+```
+    {
+      "id": string,
+      "css": string,
+      "price": number,
+      "title": string,
+      "userId": string
+    }
+```
+
+## **GET /arts/:userId**
+
+Returns all the art of the user.
+
+- **Params**
+  _Required:_ `userId=[string]`
+- **Query**
+  None
+- **Body**
+  None
+- **Headers**
+  Content-Type: application/json
+- **Cookie**
+  rds-session: `<JWT>`
+- **Success Response:**
+  - **Code:** 200
+    - **Content:**
+
+    ```
+
+    {
+        "message": "User Arts of userId <userId> returned successfully",
+        "arts": [
+            {
+            "id": string,
+            "css": string,
+            "price": number,
+            "title": string,
+            "userId": string
+            }
+        {
+    }
+    ```
+
+- **Error Response:**
+  - **Code:** 401
+    - **Content:**
+      `{ 'statusCode': 401, 'error': 'Unauthorized', 'message': 'Unauthenticated User' }`
+  - **Code:** 204
+    - **Content:**
+      `{}`
+  - **Code:** 500
+    - **Content:**
+      `{ 'statusCode': 500, 'error': 'Internal Server Error', 'message': 'An internal server error occurred' }`
+