doc: bm: LED Button Sample Alignment

Added to the nRF Bare Metal changelog that
LED and button behavior was aligned across all samples.

Signed-off-by: Martynas Smilingis <martynas.smilingis@nordicsemi.no>

Author: PizzaAllTheWay

doc/nrf-bm/release_notes/release_notes_changelog.rst

@@ -132,6 +132,8 @@ Samples
    * :ref:`ble_hids_mouse_sample`
    * :ref:`ble_hids_keyboard_sample`
 
+* Aligned LED and button behavior across samples.
+
 Bluetooth LE samples
 --------------------