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.

1991/ant/index.html

@@ -198,22 +198,18 @@ Carriage return is mapped to newline on input and ignored on output. Tab stops
 are every eight columns. Non-printable characters may have unpredictable
 results depending on the implementation of <code>curses</code>.</p>
 <h3 id="commands">Commands</h3>
-<ul>
-<li>h j k l left, down, up, right cursor movement</li>
-<li>H J K L word left, page down, page up, word right</li>
-<li><label><input type="checkbox" />beginning and end of line</label></li>
-<li>t b top and bottom of file</li>
-<li>i enter insert mode, form-feed to quit</li>
-<li>x delete character under the cursor</li>
-<li>W write buffer to file</li>
-<li>R refresh the screen</li>
-<li>Q quit</li>
-</ul>
+<pre><code>    h j k l         left, down, up, right cursor movement
+    H J K L         word left, page down, page up, word right
+    [ ]             beginning and end of line
+    t b             top and bottom of file
+    i               enter insert mode, form-feed to quit
+    x               delete character under the cursor
+    W               write buffer to file
+    R               refresh the screen
+    Q               quit</code></pre>
 <h3 id="exit-status">Exit status</h3>
-<ul>
-<li>0 success</li>
-<li>2 missing edit filename</li>
-</ul>
+<pre><code>    0               success
+    2               missing edit filename</code></pre>
 <h3 id="about-this-entry">About this entry</h3>
 <p>The <code>BUF</code> size should be set at compile time to 32767. This value was used
 because the Sozobon C compiler for the Atari ST has 16 bit ints and a limit on