doc: release: 3.1: Add notes about Atmel

Add 3.1.0 release notes for Atmel.

Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>

doc/releases/release-notes-3.1.rst

@@ -224,6 +224,8 @@ Boards & SoC Support
 
 * Made these changes in other SoC series:
 
+  * Added Atmel SAM UPLL clock support
+
 * Changes for ARC boards:
 
 * Added support for these ARM boards:
@@ -240,6 +242,9 @@ Boards & SoC Support
 
 * Made these changes in other boards:
 
+  * sam4s_xplained: Add support for HWINFO
+  * sam_e70_xlained: Add support for HWINFO and CAN-FD
+  * sam_v71_xult: Add support for HWINFO and CAN-FD
   * gd32e103v_eval: Add prescaler to timer
   * longan_nano: Add support for TF-Card slot
 
@@ -251,6 +256,8 @@ Drivers and Sensors
 
 * ADC
 
+  * Atmel SAM0: Fixed adc voltage reference
+
 * CAN
 
   * Switched from transmitting CAN frames in FIFO/chronological order to transmitting according to
@@ -280,6 +287,10 @@ Drivers and Sensors
 
 * GPIO
 
+* HWINFO
+
+  * Atmel SAM: Added RSTC support
+
 * I2C
 
 * I2S
@@ -292,6 +303,10 @@ Drivers and Sensors
 
 * Pin control
 
+  * New platforms added to ``pinctrl`` state-based API:
+
+    * Atmel SAM/SAM0
+
 * PWM
 
   * Added :c:struct:`pwm_dt_spec` and associated helpers, e.g.
@@ -369,6 +384,16 @@ Libraries / Subsystems
 HALs
 ****
 
+* Atmel
+
+  * Added dt-bindings, documentation and scripts to support state-based pin
+    control (``pinctrl``) API.
+  * Imported new SoCs header files:
+
+    * SAML21
+    * SAMR34
+    * SAMR35
+
 * GigaDevice
 
   * Fixed GD32_REMAP_MSK macro