clarify files secretGenerator

- file contents should not be base64 encoded
- full filenames are used for the secret's keys

Author: Henni

content/en/docs/tasks/configmap-secret/managing-secret-using-kustomize.md

@@ -35,7 +35,7 @@ secretGenerator:
   - password=1f2d1e2e67df
 {{< /tab >}}
 {{% tab name="Files" %}}
-1.  Store the credentials in files with the values encoded in base64:
+1.  Store the credentials in files. The filenames will be the keys of the secret:
 
     ```shell
     echo -n 'admin' > ./username.txt
@@ -123,4 +123,4 @@ kubectl delete secret db-user-pass
 
 - Read more about the [Secret concept](/docs/concepts/configuration/secret/)
 - Learn how to [manage Secrets using kubectl](/docs/tasks/configmap-secret/managing-secret-using-kubectl/)
-- Learn how to [manage Secrets using config file](/docs/tasks/configmap-secret/managing-secret-using-config-file/)
+- Learn how to [manage Secrets using config file](/docs/tasks/configmap-secret/managing-secret-using-config-file/)