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.

authors.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: .gen-authors.sh.34894.entry.md -->
 <p style="text-align:center;">
 Jump to authors starting with: [
 <a href="#A">A</a>  
@@ -2799,6 +2800,7 @@ Location: <a href="location.html#US">US</a> - <em>United States of America</em>
 <ul>
 <li><a href="2011/zucker/index.html">2011/zucker</a> - Most shiny</li>
 </ul>
+<!-- AFTER: last line of markdown file: .gen-authors.sh.34894.entry.md -->
 
 <!-- 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 -->