Add example for controlling a fan with step mode

examples/example_fan_step_mode.py

@@ -0,0 +1,33 @@
+"""Example for Fan device."""
+import asyncio
+from xknx import XKNX
+from xknx.devices import Fan, FanSpeedMode
+
+async def main():
+    """Connect to KNX/IP bus, control a fan, and turn it off afterwards."""
+    xknx = XKNX()
+    await xknx.start()
+
+    fan = Fan(
+        xknx,
+        name="TestFan",
+        group_address_switch="1/0/12",
+        group_address_speed="1/0/14",  
+        max_step=3, 
+    )
+
+    # Turn on the fan
+    await fan.turn_on()
+
+    # Set fan speed in steps
+    for step in range(1, fan.max_step + 1):
+        await fan.set_speed(step)
+        await asyncio.sleep(1)
+
+    # Turn off the fan
+    await fan.turn_off()
+
+    await xknx.stop()
+
+asyncio.run(main())
+