Update Test Cases doc to reflect removed feature_id and added test_case_steps support

Author: aliaksandr5filippov

src/pages/docs/api/test-cases.md

@@ -123,7 +123,7 @@ In the response, the steps field is returned as `steps` (not `test_case_steps` a
 
 ## Update test case
 
-Updates the top-level fields of a test case. Test case steps are not managed through this endpoint.
+Updates the top-level fields of a test case, and optionally its test case steps.
 
 **Endpoint:** `PUT /products/{product_id}/test_cases/{test_case_id}`
 
@@ -132,14 +132,21 @@ Updates the top-level fields of a test case. Test case steps are not managed thr
 - `product_id` (number, required) - ID of the Product
 - `test_case_id` (number, required) - ID of the Test Case
 
-All attributes must be provided inside the root object `test_case`. All fields are optional — only the fields you provide are updated.
+All attributes must be provided inside the root object `test_case`. All fields are optional — only the fields you provide are updated. `feature_id` is not accepted by this endpoint.
 
 **Request Body:**
 
 - `title` (string, optional) - Title of the test case
 - `requirements` (string, optional) - Requirements of the test case
 - `target_idx` (string, optional) - Reference of the test case in other system
-- `feature_id` (number, optional) - ID of the Feature to move the test case to. Must belong to the same product.
+- `test_case_steps` (array[Step], optional) - Array of step objects to create, update, or remove
+
+**Step Object:**
+
+- `id` (number, optional) - ID of an existing step to update or remove. Omit to add a new step.
+- `description` (string, optional) - Description of the step
+- `target_idx` (string, optional) - Reference of the test case step in other system
+- `_destroy` (boolean, optional) - Set to `true` to remove the step identified by `id`
 
 **Example Request:**
 
@@ -151,7 +158,12 @@ curl -X PUT "https://api.test.io/customer/v2/products/1/test_cases/123" \
   -H "Content-Type: application/json" \
   -d '{
     "test_case": {
-      "title": "Login Test (updated)"
+      "title": "Login Test (updated)",
+      "test_case_steps": [
+        { "id": 456, "description": "Navigate to login page (updated)" },
+        { "description": "Confirm dashboard is shown" },
+        { "id": 789, "_destroy": true }
+      ]
     }
   }'
 ```
@@ -162,6 +174,10 @@ curl -X PUT "https://api.test.io/customer/v2/products/1/test_cases/123" \
 
 Returns the updated test case object. See the response shape in [Create a bulk of test cases](#create-a-bulk-of-test-cases) above.
 
+{% callout type="note" %}
+If the test case is already in use by a test cycle, its steps are not edited in place — a hidden shadow copy of the test case is created (or reused) and the step changes are applied there instead, so historical test results tied to the original steps remain intact. In that case the response is the shadow copy: it has a different `id` from the one in the request URL, and subsequent requests should use that new `id`. The original `test_case_id` will then return `404` from [Get test case](#get-test-case), same as a deleted-but-in-use test case.
+{% /callout %}
+
 ## Delete test case
 
 Deletes the specified test case from the product.