fix(swagger): document 204 response for free page hinting start/stop

The PATCH /balloon/hinting/start and PATCH /balloon/hinting/stop
endpoints return 204 No Content on success (their VmmAction handlers map
to VmmData::Empty, which the API server converts to
StatusCode::NoContent), but the OpenAPI spec declared 200.

Signed-off-by: Nikita Kalyazin <nikita.kalyazin@e2b.dev>

Author: kalyazin

CHANGELOG.md

@@ -90,6 +90,10 @@ and this project adheres to
 - [#5818](https://github.com/firecracker-microvm/firecracker/pull/5818): Reject
   device status writes that clear previously set bits in the MMIO transport,
   except for reset.
+- [#5884](https://github.com/firecracker-microvm/firecracker/pull/5884):
+  Corrected the OpenAPI spec for `PATCH /balloon/hinting/start` and
+  `PATCH /balloon/hinting/stop` to declare `204 No Content` instead of `200`,
+  matching the actual runtime response.
 
 ## [1.15.0]
 

src/firecracker/swagger/firecracker.yaml

@@ -181,7 +181,7 @@ paths:
           schema:
             $ref: "#/definitions/BalloonStartCmd"
       responses:
-        200:
+        204:
           description: Free page hinting run started.
         400:
           description: The balloon free hinting was not enabled when the device was configured.
@@ -215,7 +215,7 @@ paths:
       summary: Stops a free page hinting run only if enabled pre-boot.
       operationId: stopBalloonHinting
       responses:
-        200:
+        204:
           description: Free page hinting run stopped.
         400:
           description: The balloon free hinting was not enabled when the device was configured.