Corrected example and scan interval info (#10316)

* Corrected example and scan interval info

slave: 1 option in platform configuration causes an error on 0.98.2 
added scan_interval: info
also it seems to me ha_iot_class: should be Local Pull because Modbus all about Pull data from slaves by master

* Update switch.modbus.markdown

source/_components/switch.modbus.markdown

@@ -18,7 +18,6 @@ To use your Modbus switches in your installation, add the following to your `con
 # Example configuration.yaml entry
 switch:
   platform: modbus
-  slave: 1
   coils:
     - name: Switch1
       hub: hub1
@@ -115,3 +114,24 @@ register:
       default: same as command_off
       type: integer
 {% endconfiguration %}
+
+It's possible to change the default 30 seconds scan interval for the switch state updates as shown in the [Platform options](/docs/configuration/platform_options/#scan-interval) documentation.
+
+### Full example
+
+Example a temperature sensor with a 10 seconds scan interval:
+
+```yaml
+switch:
+  platform: modbus
+  scan_interval: 10
+  coils:
+    - name: Switch1
+      hub: hub1
+      slave: 1
+      coil: 13
+    - name: Switch2
+      hub: hub1
+      slave: 2
+      coil: 14
+```