Use new target_* options in documentation

Various iscsi_* options were replaced with target_* options. The former
were initially deprecated and have now been removed.

This patch updates relevant documentation to use the new names.

There were some other hits in the documentation and code for these
names, but these appeared to be for third-party drivers, and I don't
have the context about which, if any, need to change.

Change-Id: Ic37ea85f4ec778644bc9d49f513e58dc28c87907

contrib/block-box/etc/cinder.conf

@@ -21,6 +21,6 @@ connection = mysql+pymysql://cinder:password@mariadb/cinder?charset=utf8
 lvm_type = thin
 volume_driver = cinder.volume.drivers.lvm.LVMVolumeDriver
 volume_group = cinder-volumes
-iscsi_protocol = iscsi
-iscsi_helper = tgtadm
+target_protocol = iscsi
+target_helper = tgtadm
 volume_backend_name=lvm

contrib/block-box/etc/cinder.conf.keystone

@@ -1,7 +1,7 @@
 [DEFAULT]
 rootwrap_config = /etc/cinder/rootwrap.conf
 api_paste_confg = /etc/cinder/api-paste.ini
-iscsi_helper = tgtadm
+target_helper = tgtadm
 volume_name_template = volume-%s
 volume_group = cinder-volumes
 verbose = True

contrib/block-box/etc/cinder.conf.sf

@@ -1,7 +1,7 @@
 [DEFAULT]
 rootwrap_config = /etc/cinder/rootwrap.conf
 api_paste_confg = /etc/cinder/api-paste.ini
-iscsi_helper = tgtadm
+target_helper = tgtadm
 volume_name_template = volume-%s
 volume_group = cinder-volumes
 verbose = True