Update iprop_master_ulogsize documentation

When we removed the maximum number of ulog entries (#7368), we did not
update the documentation for that parameter in kdc.conf.  Reported by
Richard Basch.

(cherry picked from commit 5fa7e666bd81a2222b155bdf3f0c3fc1bc3fabf5)

https://github.com/krb5/krb5/commit/76b99c557265f2f960477976ce89d9c5f60a7177
Author: Greg Hudson <ghudson@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 76b99c557265f2f960477976ce89d9c5f60a7177
Branch: krb5-1.11
 doc/admin/conf_files/kdc_conf.rst |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)