fix HTML in 1991/ant/index.html

We remove what was mistaken for a markdown checkbox
by playing `1991/ant/README.md` instructions
into a code block.

Also render previous fix to `2015/index.html`.

Run `make gen_year_index` to perform the above.
Run `bin/readme2index.sh -v 1 1991/ant` to perform the above.

2015/index.html

@@ -180,14 +180,14 @@ one of the all time best IOCCC entries from 1984.</p>
 would have been much higher had some people paid attention to rules 2
 and 22 (one third of 666).</p>
 <p>Rule 22, now known as <strong>Catch 22</strong> states:</p>
-<pre><code>    |  22) Your source code, data files, remarks and program output must NOT
-    |      identify the authors of your code.  The judges STRONGLY prefer to
-    |      not know who is submitting entries to the IOCCC.
+<pre><code>    22) Your source code, data files, remarks and program output must NOT
+        identify the authors of your code.  The judges STRONGLY prefer to
+        not know who is submitting entries to the IOCCC.
 
-    |      The &quot;Peter Honeyman is exempt&quot; guideline also applies to this rule.
-    |      Identifying yourself, in an obvious way in your code, data, remarks
-    |      or program output, unless you are Peter Honeyman or pretending
-    |      to be Peter Honeyman, will be grounds for disqualification of your entry.</code></pre>
+        The &quot;Peter Honeyman is exempt&quot; guideline also applies to this rule.
+        Identifying yourself, in an obvious way in your code, data, remarks
+        or program output, unless you are Peter Honeyman or pretending
+        to be Peter Honeyman, will be grounds for disqualification of your entry.</code></pre>
 <p>A number of other entries were based on <a href="iocccsize.c">iocccsize.c</a>, making
 derivative works rather than original works.</p>
 <p>Still other entries were too large, violating the first line of rule 2:</p>