Update comments for RFC 3244 kpasswd extensions

Remove the inaccurate comments "unused" and replace them with
more useful representations of what they mean.

https://github.com/krb5/krb5/commit/f2cec6d908a8b15908f4de199540e5ad3486882b
Author: Ben Kaduk <kaduk@mit.edu>
Commit: f2cec6d908a8b15908f4de199540e5ad3486882b
Branch: master
 src/include/krb5/krb5.hin |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)