Update using-ldap.md (#55574)

Co-authored-by: Kevin Heis <heiskr@users.noreply.github.com>

Author: stacycarter

content/admin/managing-iam/using-ldap-for-enterprise-iam/using-ldap.md

@@ -220,3 +220,5 @@ Log events for LDAP appear in systemd journal logs on {% data variables.location
 ## Limitations for LDAP on {% data variables.product.prodname_ghe_server %}
 
 The {% data variables.product.prodname_ghe_server %} LDAP authentication timeout setting is 10 seconds. This means that all LDAP queries required for user authentication and group membership queries (when Administrators and Restricted User Groups are configured in the management console) must successfully complete within 10 seconds for an LDAP user who is logging into {% data variables.product.prodname_ghe_server %}. {% data variables.product.prodname_ghe_server %} does not currently support extending this 10 second LDAP authentication timeout as this can have a negative impact on other services on the appliance and lead to poor performance or unexpected outages. We recommend limiting the network latency between {% data variables.product.prodname_ghe_server %} and LDAP server(s) to help prevent authentication timeouts.
+
+{% data variables.product.prodname_ghe_server %} does not support user LDAP DNs with special characters. If there is an LDAP user with a special character in their LDAP DN, {% data variables.product.prodname_ghe_server %} may not be able to accurately determine the group membership of a user who is authenticating or being synced by LDAP Sync.