Added config validation

main.go

@@ -44,7 +44,7 @@ type Config struct {
 		ApiUrl       string `toml:"api_url"`
 		SharedSecret string `toml:"shared_secret"`
 		City         string `toml:"city"`
-	} `toml:"hmc"`
+	}
 	Postmark struct {
 		ServerToken   string `toml:"server_token"`
 		ApiUrl        string `toml:"api_url"`