Release Note: Support for dns_canonicalize_hostname in krb5.conf

The [`dns_canonicalize_hostname` flag](https://web.mit.edu/kerberos/krb5-devel/doc/admin/conf_files/krb5_conf.html) in the `krb5.conf` configuration file is now supported by the JDK Kerberos implementation. When set to "true", a short hostname in a service principal name will be canonicalized to a fully qualified domain name if available. Otherwise, no canonicalization is performed. The default value is "true". This is also the behavior before JDK 12.