docs: Update i2c API modified version to 3.2
docs: Update i2c API modified version to 3.2

Updates the API overview page describing that the i2c API has been modified
for 3.2.

Signed-off-by: Tom Burdick <63c280986e32082c9e27a1a69ac8b19e3d0c6b4b@intel.com>

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