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.

1993/lmfjyh/index.html

@@ -151,6 +151,7 @@ Location: <a href="../../location.html#FI">FI</a> - <em>Republic of Finland </em
 <!-- END: this line ends content for HTML phase 20 by: bin/output-index-author.sh via bin/md2html.sh -->
 <!-- START: this line starts content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
 
+<!-- BEFORE: 1st line of markdown file: 1993/lmfjyh/README.md -->
 <h2 id="to-build">To build:</h2>
 <p>If you have gcc &lt; 2.3.3 you can build this entry like:</p>
 <pre><code>    make all</code></pre>
@@ -300,6 +301,7 @@ be new standard.</p>
         https://creativecommons.org/licenses/by-sa/4.0/
 
 -->
+<!-- AFTER: last line of markdown file: 1993/lmfjyh/README.md -->
 
 <!-- END: this line ends content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
 <!-- START: this line starts content for HTML phase 22 by: bin/output-index-inventory.sh via bin/md2html.sh -->