Rephrase and correct.

wiki/src/contribute/design/memory_erasure.mdwn

@@ -68,7 +68,9 @@ initscript replaces the `kexec` one in order to support the case when
 the boot medium is not available anymore at the time this script runs;
 it also provides an improved user interface more suitable for Tails
 target users needs. Finally, the standard Debian `halt` and `reboot`
-initscripts are disabled as 
+initscripts are taken over by having the `tails-kexec` initscript run
+before they have a chance to be run (implemented with `Required-Stop`
+in the LSB headers).
 
 - [[!tails_gitweb config/chroot_local-patches/run_kexec-load_on_halt.diff]]
 - [[!tails_gitweb config/chroot_local-includes/etc/init.d/tails-kexec]]