add example in help

remove old references in help to ncvar

@tsg_nc/tsg_nc.m

 function ncv = tsg_nc( varargin )
 
-% tsg_nc/tsg_nr -- Constructor for "tsg_nc" class.
+% tsg_nc/tsg_nc -- Constructor for "tsg_nc" class.
 % tsg_nc(varargin) constructs a 'tsg_nc' object from 
 % supplied csv 'filename'.
 %
-% Usage:  nca = tsg_ncvar( file )
+% Usage:  
+%          nc = tsg_nc( file )
+%
+% Example:
+%          ncv = tsg_nc('tsg_ncvar.csv')
 %
 % Input
 % -------
@@ -12,9 +16,9 @@ function ncv = tsg_nc( varargin )
 %
 % Output
 % --------
-% ncv      ........... instance of tsg_ncvar object
+% nc       ........... instance of tsg_nc object
 %
-% See also: methods('tsg_ncvar').
+% See also: methods('tsg_nc').
 % 
 % $Id$