Get rid of an obsolete comment.

Auditors: eater

Test plan:
None

Author: csilvers

Makefile

@@ -16,7 +16,6 @@ deps:
 
 # Pack all files in exercises/ into exercises-packed/, unless the one
 # in exercises-packed is newer.
-# This needs 'bundle' on your system, to install needed ruby modules.
 pack packed: deps
 	args=`cd exercises && find * -name '*.html' | while read infile; do outfile="../exercises-packed/$$infile"; echo "$$outfile" | xargs dirname | xargs mkdir -p; [ "$$outfile" -nt "$$infile" ] || echo "exercises/$$infile::exercises-packed/$$infile"; done`; echo "$$args" | tr ' ' '\012'; [ -z "$$args" ] || node build/pack.js $$args