As user Bitcoin has already pointed out, using a bootstrap.dat is no longer recommended—you can see the release notes for the new faster-synchronization feature here.
As a result, the bootstrap.dat torrent links were removed from bitcoin.org after a short discussion.
The bootstrap.dat file is still available here on the bitcointalk.org forum, and jgarzik has indicated that he will continue to occasionally update it "for academic research and development purposes."
Another alternative is the version which has been maintained by Armory Technologies, available here. At the time of this writing, it is more up-to-date than jgarzik's bootstrap.dat, however it's not clear if it will receive any future updates.