Update timeout script-args to use standard timespec

Many scripts were documented as using timespecs (10s, 5000ms, etc) for
timeout script-args, but one 1 or 2 actually did. Now all timeout
script-args will accept timespecs, except those which took a number of
milliseconds, which remain unchanged.

Also fixed some documentation issues (missing script name in arg
description, missing nsedoc for args, etc)

scripts/nessus-xmlrpc-brute.nse

@@ -20,6 +20,7 @@ Performs brute force password auditing against a Nessus vulnerability scanning d
 -- |_    Performed 1933 guesses in 26 seconds, average tps: 73
 --
 -- @args nessus-xmlrpc-brute.threads sets the number of threads.
+-- @args nessus-xmlrpc-brute.timeout socket timeout (milliseconds) for connecting to Nessus (default 5000)
 
 author = "Patrik Karlsson"