handbook/bsdinstall: Remove defunct hardening options

The bsdinstall hardening script no longer offers knobs for
disable_sendmail or enable_aslr.

By default, sendmail is now disabled and ASLR enabled.
No need to document this in chapter for fresh installations.

Submitted by:     bigsneaky@duck.com

Author: BigSneakyDuck

documentation/content/en/books/handbook/bsdinstall/_index.adoc

@@ -1070,10 +1070,8 @@ Here is a summary of the options that can be enabled in this menu:
 * `random_pid` - Randomize the PID of processes.
 * `clear_tmp` - Clean `/tmp` when the system starts up.
 * `disable_syslogd` - Disable opening the syslogd network socket. By default, FreeBSD runs syslogd in a secure way with `-s`. This prevents the daemon from listening for incoming UDP requests on port 514. With this option enabled, syslogd will instead run with `-ss`, which prevents syslogd from opening any port. For more information, see man:syslogd[8].
-* `disable_sendmail` - Disable the sendmail mail transport agent.
 * `secure_console` - Make the command prompt request the `root` password when entering single-user mode.
 * `disable_ddtrace` - DTrace can run in a mode that affects the running kernel. Destructive actions may not be used unless explicitly enabled. Use `-w` to enable this option when using DTrace. For more information, see man:dtrace[1].
-* `enable_aslr` - Enable address layout randomization. For more information about address layout randomization the link:https://en.wikipedia.org/wiki/Address_space_layout_randomization[Wikipedia article] can be consulted.
 
 [[bsdinstall-addusers]]
 === Add Users