Fix various NSEDoc problems.

Found by David Matousek.
http://seclists.org/nmap-dev/2013/q1/88

scripts/ip-forwarding.nse

@@ -24,6 +24,8 @@ to be on the LAN.
 -- @usage
 -- sudo nmap -sn <target> --script ip-forwarding --script-args='target=www.example.com'
 --
+-- @args ip-forwarding.target the host to which to attempt forwarding (required).
+--
 -- @output
 -- | ip-forwarding: 
 -- |_  The host has ip forwarding enabled, tried ping against (www.example.com)

scripts/irc-botnet-channels.nse

@@ -40,6 +40,8 @@ categories = {"discovery", "vuln", "safe"}
 -- @usage
 -- nmap -p 6667 --script=irc-botnet-channels --script-args 'irc-botnet-channels.channels={chan1,chan2,chan3}' <target>
 --
+-- @args irc-botnet-channels.channels a list of channel names to check for.
+--
 -- @output
 -- | irc-botnet-channels:
 -- |   #loic

scripts/jdwp-exec.nse

@@ -19,14 +19,10 @@ accepts a shell command as its argument.
 
 ]]
 
-author = "Aleksandar Nikolic" 
-license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
-categories = {"safe","discovery"}
-
 ---
 -- @usage nmap -sT <target> -p <port> --script=+jdwp-exec --script-args cmd="date"
 --
--- @args cmd 	Command to execute on the remote system.
+-- @args jdwp-exec.cmd 	Command to execute on the remote system.
 --
 -- @output 
 -- PORT     STATE SERVICE REASON
@@ -36,6 +32,10 @@ categories = {"safe","discovery"}
 -- |   Sat Aug 11 15:27:21 Central European Daylight Time 2012
 -- |_
 
+author = "Aleksandar Nikolic"
+license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
+categories = {"safe","discovery"}
+
 portrule = function(host, port)
         -- JDWP will close the port if there is no valid handshake within 2
 	-- seconds, Service detection's NULL probe detects it as tcpwrapped.

scripts/jdwp-inject.nse

@@ -16,20 +16,20 @@ You can specify your own .class file to inject by <code>filename</code> argument
 See nselib/data/jdwp-class/README for more.
 ]]
 
-author = "Aleksandar Nikolic" 
-license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
-categories = {"safe","discovery"}
-
 ---
 -- @usage nmap -sT <target> -p <port> --script=+jdwp-inject --script-args filename=HelloWorld.class
 --
--- @args filename	Java .class file to inject.
+-- @args jdwp-inject.filename	Java <code>.class</code> file to inject.
 -- @output
 -- PORT     STATE SERVICE REASON
 -- 2010/tcp open  search  syn-ack
 -- | jdwp-inject:
 -- |_  Hello world from the remote machine!
---
+
+author = "Aleksandar Nikolic"
+license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
+categories = {"safe","discovery"}
+
 portrule = function(host, port)
         -- JDWP will close the port if there is no valid handshake within 2
 	-- seconds, Service detection's NULL probe detects it as tcpwrapped.

scripts/stuxnet-detect.nse

@@ -19,7 +19,7 @@ for the filename is given on the command line.
 -- nmap --script stuxnet-detect -p 445 <host>
 --
 -- @args stuxnet-detect.save Path to save Stuxnet executable under, with
---       <code>%h/code> replaced by the host's IP address, and <code>%v</code>
+--       <code>%h</code> replaced by the host's IP address, and <code>%v</code>
 --       replaced by the version of Stuxnet.
 --
 -- @output

scripts/wsdd-discover.nse

@@ -14,7 +14,7 @@ services (.NET 4.0 or later).
 
 ---
 -- @usage
--- sudo ./nmap --script broadcast-wsdd-discover 
+-- sudo ./nmap --script wsdd-discover
 --
 -- @output
 -- PORT     STATE         SERVICE