Update docs with more howto examples (#968)

Co-authored-by: Teemu R. <tpr@iki.fi>

kasa/interfaces/lighteffect.py

@@ -1,4 +1,44 @@
-"""Module for base light effect module."""
+"""Interact with a TPLink Light Effect.
+
+>>> from kasa import Discover, Module, LightState
+>>>
+>>> dev = await Discover.discover_single(
+>>>     "127.0.0.3",
+>>>     username="user@example.com",
+>>>     password="great_password"
+>>> )
+>>> await dev.update()
+>>> print(dev.alias)
+Living Room Bulb
+
+Light effects are accessed via the LightPreset module. To list available presets
+
+>>> if dev.modules[Module.Light].has_effects:
+>>>     light_effect = dev.modules[Module.LightEffect]
+>>> light_effect.effect_list
+['Off', 'Party', 'Relax']
+
+To view the currently selected effect:
+
+>>> light_effect.effect
+Off
+
+To activate a light effect:
+
+>>> await light_effect.set_effect("Party")
+>>> await dev.update()
+>>> light_effect.effect
+Party
+
+If the device supports it you can set custom effects:
+
+>>> if light_effect.has_custom_effects:
+>>>     effect_list = { "brightness", 50 }
+>>>     await light_effect.set_custom_effect(effect_list)
+>>> light_effect.has_custom_effects  # The device in this examples does not support \
+custom effects
+False
+"""
 
 from __future__ import annotations