esp32: pinctrl: update bindings and documentation
esp32: pinctrl: update bindings and documentation

- update pinctrl bindings to use pin grouping
- update pinctrl documentation

Signed-off-by: Glauber Maroto Ferreira <dedf8e032f416c6160988666098d376154426ed6@espressif.com>

zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr