fcst: Fix FCoE target setup instructions

The FCST setup has stale step references and an invalid target enable
path. A reader following it reaches the wrong prerequisites and cannot
address enabled after entering the target directory.

Commit 87bde8ab0e ("fcst/README: Update this README file") shortened
the procedure without updating its cross-references. Commit 7a12737c9d
("Simplify README by eliminating example using of ini_groups.") changed
the LUN setup but left $LPORT duplicated in the following path.

Repair the references, terminology and relative enable command,
and clarify the LUN 0 compatibility note. The same procedure installs
packages, creates an FCoE interface, loads modules and exports storage,
so require authorization for the host, CNA, fabric, initiators and
backing devices before it is run.

fcst/README

@@ -19,6 +19,13 @@ Building and Installing
 FCST is a kernel module that depends on libfc and SCST to provide FC target
 support.
 
+WARNING: The procedure below installs system packages, creates an FCoE
+interface, loads kernel modules, changes live SCST sysfs state, exposes LUNs,
+and may reset an initiator interface. Use it only with authorization for the
+exact host, Ethernet fabric, CNA, initiators, and backing storage. Substitute
+and verify every interface name, port name, and SCST device before running a
+command.
+
 1.  Build and install scst, fcst and scstadmin following the instructions
     in the top-level INSTALL.md file.
 
@@ -39,8 +46,8 @@ support.
     over a full-duplex loss-less link (enable pause on both sides).
     Alternatively, the other end can be an FCoE switch.
 
-5.  Use fcc (part of the open-fcoe contrib tools in step 7) to see the
-    initiator setup.  To get the FCoE port name for eth3
+5.  Use fcc from the open-fcoe contrib tools to inspect the initiator
+    setup and obtain the FCoE port name for eth3:
 
 	# fcc
 	FC HBAs:
@@ -58,8 +65,8 @@ support.
 
 	modprobe fcst
 
-7.  Add any disks (configured in step 8) you want to export
-     Note that you must have a LUN 0.
+7.  Add the SCST devices configured in step 3 that you want to export.
+    Many initiators require a LUN 0.
 
 	LPORT=20:00:00:1b:21:06:58:21		# the local Port_Name
 
@@ -67,9 +74,9 @@ support.
 	echo add disk-name 0 > luns/mgmt
 	echo add disk-name 1 > luns/mgmt
 
-8.  Enable the initiator:
+8.  Enable the target:
 
-	echo 1 > $LPORT/enabled
+	echo 1 > enabled
 
 9.  As a temporary workaround, you may need to reset the interface
     on the initiator side so it sees the SCST device as a target and