Mention need for --no-inc-recursive in rsync command

Mention need for --no-inc-recursive in rsync command

Since rsync 3.0.0 (released in 2008), the default way to enumerate
changes was changed in a way that makes it less likely that the hardlink
sync mode works. Since the whole point of the documented procedure is
for the hardlinks to work, change our docs to suggest using the
backwards compatibility switch.