krb5 commit [krb5-1.21]: Document dns_lookup_realm relation

[ghudson at mit.edu]

https://github.com/krb5/krb5/commit/f5fa6ee0ab075f48426b2bfc58fafcbff459442a
commit f5fa6ee0ab075f48426b2bfc58fafcbff459442a
Author: Greg Hudson <ghudson at mit.edu>
Date:   Mon Aug 5 17:37:06 2024 -0400

    Document dns_lookup_realm relation
    
    (cherry picked from commit bcc0dda256b184f8d87a4587f3f3997770020c87)
    
    ticket: 9134
    version_fixed: 1.21.4

 doc/admin/conf_files/krb5_conf.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/admin/conf_files/krb5_conf.rst b/doc/admin/conf_files/krb5_conf.rst
index ecdf91750..313b55bfa 100644
--- a/doc/admin/conf_files/krb5_conf.rst
+++ b/doc/admin/conf_files/krb5_conf.rst
@@ -221,6 +221,12 @@ The libdefaults section may contain any of the following relations:
     data), and anything the fake KDC sends will not be trusted without
     verification using some secret that it won't know.
 
+**dns_lookup_realm**
+    Indicate whether DNS TXT records should be used to map hostnames
+    to realm names for hostnames not listed in the [domain_realm]
+    section, and to determine the default realm if **default_realm**
+    is not set.  The default value is false.
+
 **dns_uri_lookup**
     Indicate whether DNS URI records should be used to locate the KDCs
     and other servers for a realm, if they are not listed in the