Right now, the `nextboot(8)` manual page suggests that the `loader(8)` would delete the `/boot/nextboot.conf` file which is 1) not the most user-friendly way of working with custom configurations, and 2) simply not true.
In reality, what happens is that when next-boot kernel is being configured, `nextboot_enable="YES"` line is added at the top of that file. After `loader(8)` reads the configuration, it would **not delete** it, but simply change the setting to `"NO"`, that is, **disable** it.
While were, add one missing serial (Oxford) comma and fix some bogus line wraps along the way.