Update default doc default for bind_host to match previous change
http://review.openstack.org/386817/
Change-Id: Iff048ba7152c1b7e945f284311215c8f872c1409
Closes-bug: #
1640104
#
# [*bind_host*]
# The host/ip address Apache will listen on.
-# Optional. Defaults to undef (listen on all ip addresses).
+# Optional. Defaults to hiera('controller_host')
#
# [*ui_port*]
# The port on which the UI is listening.