doc: migration/release: 3.7: Add LED strip changes

Adds changes about the LED strip driver

Signed-off-by: Jamie McCrae <spam@helper3000.net>

Author: thedjnK

doc/releases/migration-guide-3.7.rst

@@ -252,6 +252,14 @@ LED Strip
 * The property ``in-gpios`` defined in :dtcompatible:`worldsemi,ws2812-gpio` has been
   renamed to ``gpios``. (:github:`68514`)
 
+* The ``chain-length`` and ``color-mapping`` properties have been added to all LED strip bindings
+  and are now mandatory.
+
+* Added a new mandatory ``length`` function which returns the length (number of pixels) of an LED
+  strip device.
+
+* Made ``update_channels`` function optional and removed unimplemented functions.
+
 Sensors
 =======
 

doc/releases/release-notes-3.7.rst

@@ -207,6 +207,11 @@ Drivers and Sensors
 
 * Input
 
+* LED Strip
+
+  * The ``chain-length`` and ``color-mapping`` properties have been added to all LED strip
+    bindings.
+
 * MDIO
 
 * MFD