Updates to the Kerberos section:
- prefer sysrc to manual edits of /etc/rc.conf
- Add pkg install step
- provide the full path to the kadmind.acl file
- Updated messages from kadmin add command
- Update Heimdal wiki link
I changed only minor details in the original patch to
conform to our doc style and conventions.
Submitted by: farhan_farhan.codes
Approved by: bcr@
Differential Revision: https://reviews.freebsd.org/D23596