add/fix missing backtick

Author: Yannic Haupenthal

files/gitlab-config-template/gitlab.rb.template

@@ -2774,7 +2774,7 @@ external_url 'GENERATED_EXTERNAL_URL'
 ##! Note: We do not recommend changing these values unless absolutely necessary
 ##! Set to false to only parse secrets from `gitlab-secrets.json` file but not generate them.
 # package['generate_default_secrets'] = true
-##! Set to false to prevent creating the default gitlab-secrets.json` file
+##! Set to false to prevent creating the default `gitlab-secrets.json` file
 # package['generate_secrets_json_file'] = true
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