`pdMS_TO_TICKS()` converts milliseconds to RTOS ticks portably across tick rate configs

FreeRTOS timing functions take ticks, not milliseconds. If you hardcode `vTaskDelay(100)` you get 100 ticks, whose real-time duration depends on `configTICK_RATE_HZ`. At 1000 Hz that is 100 ms; at 100 Hz it is 1000 ms. `pdMS_TO_TICKS(ms)` does the conversion correctly regardless of the tick rate, so the same source code produces the same real-time delay on any configuration. Always use it instead of a bare integer literal.

/* I delay for 250 ms regardless of the configured tick rate */
vTaskDelay(pdMS_TO_TICKS(250));

/* I set a 1 second timeout on a queue receive */
xQueueReceive(xQueue, &item, pdMS_TO_TICKS(1000));

/* The macro: (portTickType)((ms * configTICK_RATE_HZ) / 1000) */
/* Hardcoding 250 is only correct when configTICK_RATE_HZ == 1000 */