forecast.io backend: clarify lat,lon-pair usage

backends/forecast.io.go

@@ -208,7 +208,7 @@ func (c *forecastConfig) Fetch(location string, numdays int) iface.Data {
 		log.Fatal("No forecast.io API key specified.\nYou have to register for one at https://developer.forecast.io/register")
 	}
 	if matched, err := regexp.MatchString(`^-?[0-9]*(\.[0-9]+)?,-?[0-9]*(\.[0-9]+)?$`, location); !matched || err != nil {
-		log.Fatalf("Error: The forecast.io backend only supports latitude,longitude pairs as location.\nTry `40.748,-73.985` instead of `%s` to get weather for New York", location)
+		log.Fatalf("Error: The forecast.io backend only supports latitude,longitude pairs as location.\nInstead of `%s` try `40.748,-73.985` for example to get a forecast for New York", location)
 	}
 
 	c.tz = time.Local