Merge branch 'feature/rtc_gpio_isolate' into 'master'

Add rtc_gpio_isolate function, use it in deep sleep examples

See merge request idf/esp-idf!1936

examples/system/console/main/cmd_system.c

@@ -155,6 +155,7 @@ static int deep_sleep(int argc, char** argv)
 
         ESP_ERROR_CHECK( esp_sleep_enable_ext1_wakeup(1ULL << io_num, level) );
     }
+    rtc_gpio_isolate(GPIO_NUM_12);
     esp_deep_sleep_start();
 }