make a man page for test_version

--- a/bin/test_version
+++ b/bin/test_version
@@ -1,7 +1,19 @@
-#!perl 
+#!/usr/bin/perl
 
 use strict;
 use warnings;
 
 use Test::HasVersion; our $VERSION = $Test::HasVersion::VERSION;
-all_pm_version_ok(@ARGV);
\ No newline at end of file
+all_pm_version_ok(@ARGV);
+
+=head1 NAME
+
+test_version - check that all Perl modules in a distribution have version numbers
+
+=head1 DESCRIPTION
+
+This script runs the Test::HasVersion tests on the distribution in the
+current directory. Test::HasVersion can also be used like normal
+tests, see the Test::HasVersion man page for how to do that.
+
+=cut
