C26941: Escaping '@' character (#6138)

Author: v-maudel

docs/framework/configure-apps/file-schema/wcf/identity.md

@@ -42,7 +42,7 @@ The identity element allows a client developer to specify at design time the exp
 |dns|Specifies the DNS of an X.509 certificate used to authenticate a service. This element contains an attribute `value` that is a string, and contains the actual identity.|  
 |rsa|Specifies the value of the RSA field of an X.509 certificate used to authenticate a service to a client. This element contains an attribute `value` that is a string, and contains the actual identity|  
 |servicePrincipalName|Specifies a server principal name (SPN) identity, which is the principal name used by a client to uniquely identify an instance of a service. This element contains an attribute `value` that is a string, and contains the actual principal name. This element is of type <xref:System.ServiceModel.Configuration.ServicePrincipalNameElement>.|  
-|userPrincipalName|Specifies a user principal name (UPN) identity, which is the logon name type of a user on a network. The user principal name consists of the user object name used in Active Directory, followed by the at symbol (@) and then, typically, the Domain Name System parent domain. For example, Jeff in the Fabrikam.com domain tree might have the user principal name [jeff@fabrikam.com](mailto:jeffsmith@fabrikam.com).  This element contains an attribute `value` that is a string, and contains the actual principal name. This element is of type <xref:System.ServiceModel.Configuration.UserPrincipalNameElement>.|  
+|userPrincipalName|Specifies a user principal name (UPN) identity, which is the logon name type of a user on a network. The user principal name consists of the user object name used in Active Directory, followed by the at symbol (\@) and then, typically, the Domain Name System parent domain. For example, Jeff in the Fabrikam.com domain tree might have the user principal name [jeff@fabrikam.com](mailto:jeffsmith@fabrikam.com).  This element contains an attribute `value` that is a string, and contains the actual principal name. This element is of type <xref:System.ServiceModel.Configuration.UserPrincipalNameElement>.|  
   
 ### Parent Elements