[KYUUBI #4362] Add _configurations in kerberos.rst

### _Why are the changes needed?_

Add `_configurations` in kerberos.rst

### _How was this patch tested?_
- [ ] Add some test cases that check the changes thoroughly including negative and positive cases if possible

- [ ] Add screenshots for manual tests if appropriate

- [x] [Run test](https://kyuubi.readthedocs.io/en/master/develop_tools/testing.html#running-tests) locally before make a pull request

Closes #4362 from Yikf/kerberos-doc-config.

Closes #4362

d8f1976 [Yikf] Add _configurations in kerberos.rst

Authored-by: Yikf <yikaifei@apache.org>
Signed-off-by: liangbowen <liangbowen@gf.com.cn>

docs/security/kerberos.rst

@@ -115,4 +115,5 @@ Refresh all the kyuubi server instances
 Restart all the kyuubi server instances or `Refresh Configurations`_ to activate the settings.
 
 .. _Hadoop Impersonation: https://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-common/Superusers.html
+.. _configurations: ../client/advanced/kerberos.html
 .. _Refresh Configurations: ../tools/kyuubi-admin.html#refresh-config