change test files that do not end in .txt to view via GitHub

1994/horton/index.html

@@ -236,7 +236,7 @@ It’s easily modified to graph <em>any</em> 96x160 bitmap on a dumb terminal.</
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1994/horton/try.alt.sh">try.alt.sh</a> - how to run alternative code</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1994/horton/try.sh">try.sh</a> - how to run</li>
 <li><a href="login_sept92-pp28-31.pdf">login_sept92-pp28-31.pdf</a> - login article on graphics for dumb terminals</li>
-<li><a href="gtface.data">gtface.data</a> - data for gtfsace</li>
+<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1994/horton/gtface.data">gtface.data</a> - data for gtfsace</li>
 </ul>
 <h2 id="secondary-files">Secondary files</h2>
 <ul>