webserver: tag webserver_require_spnego as stable

This is a pretty important piece of "secure" web UI puzzle, and I don't
expect its interface to change in the future.

I also snuck in a change to add webserver_require_spnego to the security
section of /config. Screenshot: https://imgur.com/a/jdDO28I

Change-Id: Ib223431f037dfa9f4c9e3d03b03ce03555b25de7
Reviewed-on: http://gerrit.cloudera.org:8080/14872
Reviewed-by: Grant Henke <granthenke@apache.org>
Reviewed-by: Alexey Serbin <aserbin@cloudera.com>
Tested-by: Adar Dembo <adar@cloudera.com>
2 files changed