Update template fan to include speed_count (#16562)

Co-authored-by: Franck Nijhof <git@frenck.dev>

source/_integrations/fan.template.markdown

@@ -50,6 +50,7 @@ fan:
           service: script.fan_direction
           data:
             direction: "{{ direction }}"
+        speed_count: 6
         preset_modes:
           - 'auto'
           - 'smart'
@@ -122,4 +123,9 @@ fan:
         required: false
         type: [string, list]
         default: []
+      speed_count:
+        description: The number of speeds the fan supports. Used to calculate the percentage step for the `fan.increase_speed` and `fan.decrease_speed` services.
+        required: false
+        type: integer
+        default: 100
 {% endconfiguration %}