Improve try scripts for 1989/ovdluhe

When I first wrote the try scripts, and in particular the ovdluhe.alt.c
code to do what the author suggested one try, I just had the option in
try.alt.sh to redefine P once. Now the user can do that but after the
initial loop it loops from 2..10 (the range the author suggested)
running the loop again (on the three files three times) so one can see
what the author means.

The try.sh script has the updated idea by the judges of printing two
lines, not one, after each prompt.

Rebuilt index.html from updated README.md.

1989/ovdluhe/index.html

@@ -501,6 +501,8 @@ value that’s not a number.</p>
     P=5 ./try.alt.sh</code></pre>
 <p><strong>NOTE</strong>: if you specify too high a value for <code>P</code> the program might fail. If you
 specify a value &lt; 0 it will fail to compile.</p>
+<p>The script will also run the program with <code>P=2</code> through <code>P=10</code> like the author
+suggested. Send intr (usually ctrl-c) to stop early.</p>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
 <p>Run this program using your favorite text file as input. Files
 such as mailboxes, man pages and usenet articles are especially