C26883: Escaping "@" character to avoid localization issue (#6158)

Author: v-maudel

docs/framework/wcf/servicemodel-metadata-utility-tool-svcutil-exe.md

@@ -60,7 +60,7 @@ The ServiceModel Metadata Utility tool is used to generate service model code fr
  For a service with a BasicHttpContextbinding endpoint, Svcutil.exe generates a BasicHttpBinding with the `allowCookies` attribute set to `true` instead. The cookies are used for context on the server. If you would like to manage context on the client when the service uses cookies, you can manually modify the configuration to use a context binding.  
 
 > [!CAUTION]
->  Svcutil.exe generates the client based on the WSDL or policy file received from the service. The user principal name (UPN) is generated by concatenating username, "@" and a fully-qualified domain name (FQDN). However, for users who registered on Active Directory, this format is not valid and the UPN generated by the tool causes a failure in Kerberos authentication with the error message "The logon attempt failed". To resolve this problem, you should manually fix the client file generated by this tool.  
+>  Svcutil.exe generates the client based on the WSDL or policy file received from the service. The user principal name (UPN) is generated by concatenating username, "\@" and a fully-qualified domain name (FQDN). However, for users who registered on Active Directory, this format is not valid and the UPN generated by the tool causes a failure in Kerberos authentication with the error message "The logon attempt failed". To resolve this problem, you should manually fix the client file generated by this tool.  
   
  `svcutil.exe [/t:code]  <metadataDocumentPath>* | <url>* | <epr>`