doc: migration-guide-4.1: add note about nxp,kinetis-rtc change

Add note about compatible change for nxp,kinetis-rtc.

Signed-off-by: Manuel Argüelles <[email protected]>

Author: manuargue

doc/releases/migration-guide-4.1.rst

@@ -216,6 +216,11 @@ SPI
 Regulator
 =========
 
+RTC
+===
+
+* Renamed the ``compatible`` from ``nxp,kinetis-rtc`` to :dtcompatible:`nxp,rtc`.
+
 Video
 =====