Update pskov sample sites 01, 02, 03 with PSKOV reference

pskov/sample/01.TwoPages/about.html

@@ -63,6 +63,9 @@
 <p>I have used <a href="http://opengamestudio.org/pskov">PSKOV</a> static site generator to create this web site. Send all complaints to <strong>PSKOV</strong>'s authors, not me, I'm already dead.</p>
 <p>Have a look at my <a href="cv.html">CV</a> now.</p>
             </div>
+            <div id="footer">
+                This sample web site has been generated by <a href="http://opengamestudio.org/pskov">PSKOV</a>.
+            </div>
         </center>
     </body>
 </html>

pskov/sample/01.TwoPages/cv.html

@@ -89,6 +89,9 @@
 </tbody>
 </table>
             </div>
+            <div id="footer">
+                This sample web site has been generated by <a href="http://opengamestudio.org/pskov">PSKOV</a>.
+            </div>
         </center>
     </body>
 </html>