Minor documentation and code improvements

- fix name of certificate in README
- avoid unneeded variable declaration in internal/services/i18n.go

README.md

@@ -20,7 +20,7 @@ certificates used to verify client certificates to run `cacert-idp`.
 An easy way to generate server certificate and key for local testing is
 [`mkcert`](https://github.com/FiloSottile/mkcert/releases).
 
-1. Run `mkcert` to generate `idp.cacert.localhost.pem` and
+1. Run `mkcert` to generate `idp.cacert.localhost+1.pem` and
    `idp.cacert.localhost+1-key.pem`:
 
    ```shell

internal/services/i18n.go

@@ -149,8 +149,6 @@ func (m *MessageCatalog) AddMessages(messages map[string]*i18n.Message) {
 }
 
 func (m *MessageCatalog) LookupErrorMessage(tag, field string, value interface{}, localizer *i18n.Localizer) string {
-	var message *i18n.Message
-
 	message, ok := m.messages[fmt.Sprintf("%s-%s", field, tag)]
 	if !ok {
 		m.logger.Infof("no specific error message %s-%s", field, tag)
@@ -200,7 +198,7 @@ func (m *MessageCatalog) LookupMessage(
 		return translation
 	}
 
-	m.logger.Warnf("no translation found for %s", id)
+	m.logger.WithField("id", id).Warn("no translation found for id")
 
 	return id
 }