doc: migration-guide: Moved nrf_etr

Migration guide for the move of drivers/misc/nrf_etr to
drivers/debug/debug_nrf_etr.

Signed-off-by: Karsten Koenig <[email protected]>

Author: karstenkoenig

doc/releases/migration-guide-4.3.rst

@@ -61,6 +61,14 @@ Device Drivers and Devicetree
 
 .. zephyr-keep-sorted-start re(^\w)
 
+MISC
+====
+
+* The nrf_etr driver has been migrated to drivers/debug. As a consequence the related Kconfig
+  symbol was renamed from ``NRF_ETR`` to :kconfig:option:`DEBUG_NRF_ETR`, along with the rest of
+  the ``NRF_ETR`` symbols. Also the driver needs to be explicitly enabled via
+  :kconfig:option:`DEBUG_DRIVER` as it is no longer built by default.
+
 MFD
 ===