[ns] outdated example(s) in Mark Greis's tutorial

[Shashi Guruprasad <shash@cs.utah.edu>]

I wasted an hour trying to get simple-wireless.tcl downloaded off the
tutorial webpage (http://www.isi.edu/nsnam/ns/tutorial/index.html) to
work. The right version of the file is found in the allinone package
itself. I suggest that the people at VINT group either update the links or
modify the webpage(s) and say that the examples are directly available in
the NS download.

-Shashi