doc: Add Kinetis adc and pwm drivers to 1.9 release notes

Signed-off-by: Maureen Helm <[email protected]>

Author: MaureenHelm

doc/release-notes-1.9.rst

@@ -52,6 +52,7 @@ Drivers and Sensors
 * KW40Z IEEE 802.15.4 radio driver support added
 * APDS9960 sensor driver added
 * Added TICKLESS KERNEL support for nrf RTC Timer.
+* Added Kinetis adc and pwm drivers
 
 Networking
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