Added additional upgrade hints.

README.md

@@ -43,6 +43,7 @@ Version 2.0 is a major rewrite of both libraries, which removes previously depre
 1. In your startup code, replace all previous dependency injection extension methods with a version of `AddLdapAuthentication`. The template parameters allow you to change the type of user and group that the LDAP entries are mapped to.
 1. In your code, change all services to include the user and/or group type you want to use.
 1. In your code, replace `ILdapAuthenticationService.Login` with `ILdapAuthenticationService.LoginUser` or `ILdapAuthenticationService.LoginPrincipal` depending on your needs.
+1. If you use `LdapAttributeAttribute.GetLdapAttribute` to reflect on LDAP attribute mappings in your code, inject `ILdapAttributeMap<LdapUserOrGroup>` to obtain similar information. `ILdapAttributeMap`s provide direct access to attribute names and `PropertyInfo`s and are more efficient than the previous on-demand reflection.
 
 ## Differences between LdapAuthentication and DirectoryAuthentication
 [Visus.DirectoryAuthentication](Visus.DirectoryAuthentication) and [Visus.LdapAuthentication](Visus.LdapAuthentication) can mostly be used interchangeably with a few exceptions: