Fix typo in modbus integration strings.json (#115685)

homeassistant/components/modbus/strings.json

@@ -88,7 +88,7 @@
     },
     "duplicate_entity_entry": {
       "title": "Modbus {sub_1} address {sub_2} is duplicate, second entry not loaded.",
-      "description": "An address can only be associated with on entity, Please correct the entry in your configuration.yaml file and restart Home Assistant to fix this issue."
+      "description": "An address can only be associated with one entity, Please correct the entry in your configuration.yaml file and restart Home Assistant to fix this issue."
     },
     "duplicate_entity_name": {
       "title": "Modbus {sub_1} is duplicate, second entry not loaded.",