DOCS: Modified `onIMECompositionChange` documentation to bring clarity to intended usage (#1755)

* Modified the documentation for onIMECompositionChange to clear up reliance on blank string events for submission and reset

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -30,6 +30,7 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed case [ISXB-251](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-251) (Action only calls started & performed callbacks when control type is set to Vector3Composite). `EvaluateMagnitude` wasn't overridden for Vector3Composite, also made some minor changes to Vector3Composite and Vector2Composite for consistency.
 - Fixed case [ISXB-580](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-580) (UI Submit / Cancel not working with Switch Pro controller) by adding "Submit" & "Cancel" usages to the Switch Pro controller input controls.
 - Fixed an issue where undoing deletion of Action Maps did not restore Actions correctly.
+- Fixed case [ISXB-628](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-628) (OnIMECompositionChange does not return an empty string on accept when using Microsoft IME) by clarifying expectations and intended usage for the IME composition change event.
 
 ## [1.8.0-pre.1] - 2023-09-04
 

Packages/com.unity.inputsystem/InputSystem/Devices/Keyboard.cs

@@ -959,13 +959,17 @@ namespace UnityEngine.InputSystem
         }
 
         /// <summary>
-        /// An event that is fired to get IME composition strings.  Fired once for every change,
-        /// sends the entire string to date, and sends a blank string whenever a composition is submitted or reset.
+        /// An event that is fired to get IME composition strings.  Fired once for every change containing the entire string to date.
+        /// When using an IME, this event can be used to display the composition string while it is being edited. When a composition
+        /// string is submitted, one or many <see cref="Keyboard.OnTextInput"/> events will fire with the submitted characters.
         /// </summary>
         /// <remarks>
         /// Some languages use complex input methods which involve opening windows to insert characters.
         /// Typically, this is not desirable while playing a game, as games may just interpret key strokes as game input, not as text.
         ///
+        /// Many IMEs cause this event to fire with a blank string when the composition is submitted or reset, however it is best
+        /// not to rely on this behaviour since it is IME dependent.
+        ///
         /// See <see cref="Keyboard.SetIMEEnabled"/> for turning IME on/off
         /// </remarks>
         public event Action<IMECompositionString> onIMECompositionChange