fix markdown footnote problem caused by pandoc

Add "<!-- BEFORE: 1st line of markdown file: FILE/PATH -->"
before the markdown content.  This line appears in the
generated HTML.

Add "<!-- AFTER: last line of markdown file: FILE/PATH -->"
after the markdown content.  This line appears in the
generated HTML.

We test a fix relating to problems produced by `pandoc(1)`
when footnotes are added at the end of generated HTML.
This test is made for `2000/bmeyer/index.html`.

Fixed exit 4 in `bin/md2html.sh that should be exit 5.

Changed `bin/md2html.sh` VERSION from to "1.3 2024-04-14"
to "1.4 2024-04-18".

Run `bin/readme2index.sh -v 1 2000/bmeyer` to perform the above.

next/guidelines.html

@@ -132,6 +132,7 @@
 <!-- END: this line ends content from: inc/before-content.default.html -->
 <!-- START: this line starts content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
 
+<!-- BEFORE: 1st line of markdown file: next/guidelines.md -->
 <!-- START: this line starts content from: inc/guidelines.closed.hdr -->
 <h1 id="warning-these-guidelines-are-out-of-date">WARNING: These guidelines are OUT OF DATE</h1>
 <p>They are a <strong>very tentative proposal</strong> for the next IOCCC
@@ -909,7 +910,8 @@ to be sure they are seeing the most recent tweets.</p>
 <pre><code>    https://fosstodon.org/@ioccc</code></pre>
 <p><strong>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-</strong></p>
 <p>Leonid A. Broukhis<br>
-chongo (Landon Curt Noll) /\cc/\</p>
+chongo (Landon Curt Noll) /\cc/\
+<!-- AFTER: last line of markdown file: next/guidelines.md --></p>
 
 <!-- END: this line ends content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
 <!-- START: this line starts content from: inc/after-content.default.html -->