fix internal links in entry index.html from 1984 thru 2012

2006/monge/index.html

@@ -171,7 +171,7 @@ of iterations to use. See <a href="#alternate-code">Alternate code</a> below.</p
 <p>This alternate code lets you specify the width and height of the image as well
 as the number of iterations to perform.</p>
 <h3 id="alternate-build">Alternate build:</h3>
-<p>To use the default values, the same as <a href="monge.c">monge.c</a>, just do:</p>
+<p>To use the default values, the same as <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2006/monge/monge.c">monge.c</a>, just do:</p>
 <pre><code>    make alt</code></pre>
 <p>But if you wish to actually make use of it you will want to redefine one or more
 of the variables <code>W</code>, <code>H</code> and <code>I</code>. The defaults are (respectively) 400, 300 and