change inventory layout for year level index.html files

The "Jump to top" in the inventory section of an entry index.html file
now is below the secondary file list, with a short line above it.

Changed `bin/output-year-index.sh` VERSION from "1.3 2024-04-15"
to "1.4 2024-04-21".

Run `make gen_year_index` to perform the above.

1984/index.html

@@ -185,7 +185,10 @@ See also <a href="../faq.html">the IOCCC FAQ</a> for additional information on t
 <li><a href="laman/index.html">1984/laman</a> - Third place</li>
 <li><a href="mullender/index.html">1984/mullender</a> - Grand Prize</li>
 </ul>
-<p> <strong>Jump to:</strong> <a href="#">top</a></p>
+<hr style="width:10%;text-align:left;margin-left:0">
+<h4>
+Jump to: <a href="#">top</a>
+</h4>
 
 <!-- END: next line ends content generated by: bin/output-year-index.sh -->