nrelease: Add back the creation of the /usr/local hierarchy on the LiveCD.

nrelease: Add back the creation of the /usr/local hierarchy on the LiveCD.

Even though nothing in base uses it, it's more convenient to have the
hierarchy already in place in case the user wants to install some stuff
the traditional way.

While doing this, remove the documentation of the 'fetch' target from
release.7 since this target no longer exists now that cvsup has been
removed from the LiveCD.

In-discussion-with: dillon