More BSD style in diff command line

Hello all.

This patch changes GNU-style --exclude diff(1) option, that is not
ever mentioned in manual page, to -x, and add (sometimes useful) -p
to recommended diff(1) commands lines.

Not that it matters much, of course.

Index: testing.html
===================================================================
RCS file: /cvs/www/faq/ports/testing.html,v
retrieving revision 1.6
diff -u -p -r1.6 testing.html
--- testing.html	19 Sep 2010 13:35:40 -0000	1.6
+++ testing.html	6 Jan 2011 13:18:14 -0000
@@ -265,8 +265,8 @@ PERFORMANCE OF THIS DOCUMENTATION
     links, useless or missing variables, correct licensing and categories.
     Those who are more skilled can help by examining patches, as well as
     providing diffs to correct bugs, add flavors, or other enhancements.</p>
-    <p>These diffs should be done with the <tt>-uNr --exclude=CVS</tt> options.
-    <tt>cvs diff -uN</tt> can also be used to generate patches against
+    <p>These diffs should be done with the <tt>-uNprx CVS</tt> options.
+    <tt>cvs diff -uNp</tt> can also be used to generate patches against
     the CVS repository.</p>
 
 <p>