specify unified diffs rather than context diffs

[SVN r36325]

more/bugs.htm

@@ -64,7 +64,7 @@ a bug in the file <code>intentional_bug.hpp</code>:<br>
           <li>Make sure that the bug is still present in the code.</li>
           <li>Copy the file <code>intentional_bug.hpp</code> to a file called <code>intentional_bug.hpp.orig</code>.</li>
           <li>Apply your changes to <code>intentional_bug.hpp</code>.</li>
-          <li>Run "<code>diff -c intentional_bug.hpp.orig intentional_bug.hpp &gt; intentional_bug.hpp.patch</code>" from the command prompt.</li>
+          <li>Run "<code>diff -du intentional_bug.hpp.orig intentional_bug.hpp &gt; intentional_bug.hpp.patch</code>" from the command prompt.</li>
           <li>Submit the patch file together with an explanation of the bug
 and the proposed fix; and don't forget to include the word <b>patch</b> or <b>bug</b>
 in the subject if you're submitting to the <a href="http://www.boost.org/more/mailing_lists.htm#main">boost mailing list</a>.<br>