[Input System] Added CHANGELOG entry for "Add Control Scheme..." popup fix (case ISXB-1131)

Author: AlexTyrer

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -18,6 +18,7 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed ISubmitHandler.OnSubmit event processing when operating in Manual Update mode (ISXB-1141)
 - Fixed Rename mode is not entered and name is autocompleted to default when creating a new Action Map on 2022.3. [ISXB-1151](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1151)
 - Fixed unexpected control scheme switch when using `OnScreenControl` and pointer based schemes which registed "Cancel" event on every frame.[ISXB-656](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-656)
+- Fixed an issue with The "Add Control Scheme..." popup window so that it now persists until any changes are explicitly Saved or Cancelled [case ISXB-1131](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1131))
 
 ### Changed
 - Added back the InputManager to InputSystem project-wide asset migration code with performance improvement (ISX-2086)