Rename 2004/sds/README_sds.md to .txt

thanks-for-help.html

@@ -2186,7 +2186,7 @@ fast in modern systems, especially the scrolling text of
 <h2 id="sds-index.html"><a name="2004_sds"></a><a href="2004/sds/sds.c">2004/sds</a> (<a href="2004/sds/index.html">index.html</a>)</h2>
 <p><a href="#cody">Cody</a> added the <a href="2004/sds/try.sh">try.sh</a> script.</p>
 <p>Also, after the README.md file had copyright changes, it broke the script so
-Cody made a copy of the older README.md file into <code>README_sds.md</code> and added that
+Cody made a copy of the older README.md file into <code>README_sds.txt</code> and added that
 to the repo for the script instead.</p>
 <h2 id="vik2-index.html"><a name="2004_vik2"></a><a href="2004/vik2/vik2.c">2004/vik2</a> (<a href="2004/vik2/index.html">index.html</a>)</h2>
 <p><a href="#cody">Cody</a> fixed this to compile in Linux. Although it compiled cleanly in macOS (and