fix yet more broken markdown links

Fixed a link problem in `thanks-for-help.md`.

Exclude tmp from the tmp/md-*.sh tools.

thanks-for-help.html

@@ -1985,7 +1985,7 @@ characters or it might print (up to) the next 231 characters and so on.</p>
 <h3 id="source-code-schnitzi.c-1">Source code: <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1994/schnitzi/schnitzi.c">schnitzi.c</a></h3>
 </div>
 <p><a href="#cody">Cody</a> added two alt versions, <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1994/schnitzi/schnitzi.alt.c">one which uses
-<code>fgets()</code></a> but when fed its own source code cannot
+fgets_()</a> but when fed its own source code cannot
 generate code that compile and another <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1994/schnitzi/schnitzi.alt2.c">one with a bigger buffer
 size</a> which, when fed its own source code, will
 generate compilable code but not with the same buffer size but rather the