Documentation: Add GPT information to RA4M1 documentation

- Updated information about the RA4M1 microcontroller capabilities, including the General Purpose Timer (GPT).
- Added information about the PWM driver support for the Arduino R4 Minima board using the GPT timer.

Signed-off-by: leocafonso <leocafonso@gmail.com>

Author: leocafonso

Documentation/platforms/arm/ra4m1/boards/arduino-r4-minima/index.rst

@@ -83,6 +83,26 @@ easily changed by modifying the configuration.
     SWD-8                TXD1
     ==================   ============
 
+PWM Outputs
+===============
+
+The R7FA4M1ABxCFM has a GPT (General Purpose Timer) that can be used for PWM output.
+
+Any of the Arduino-r4-minima PWM outputs can be used. By default, it is disabled in all configurations.
+This can be easily changed by modifying the configuration.
+
+    ==================   ============
+    Arduino R4 Minima    R7FA4M1ABxCFM
+    Pin (Label)          SCI Mapping
+    ==================   ============
+    ~3                   GTIOC1B_P104
+    ~5                   GTIOC2B_P102
+    ~6                   GTIOC0B_P106
+    ~9                   GTIOC7B_P303
+    ~10                  GTIOC3B_P112
+    ~11                  GTIOC1A_P109
+    ==================   ============
+
 Loading Code
 ============
 

Documentation/platforms/arm/ra4m1/index.rst

@@ -35,12 +35,12 @@ KINT        No
 ELC         No
 DTC         No
 DMAC        No
-GPT         No
+GPT         Yes      Just PWM
 AGT         No
 RTC         No
 WDT         No
 IWDT        No
-SCI         Yes       Just UART
+SCI         Yes      Just UART
 IIC         No
 SPI         No
 SSIE        No
@@ -71,10 +71,13 @@ Nuttx driver support UART mode (No-FIFO).
 GPIO
 -----
 
-
-
 Pins can be configured/operated using ``ra_gpio_*`` functions.
 
+GPT
+----
+General Purpose Timer (GPT) is a multi-function timer that can be used in various modes such as PWM output, input capture, output compare, and interval timer.
+Nuttx driver support PWM mode.
+
 Supported Boards
 ================