convert leading TAB chars into 8 spaces before running pandoc

The `bin/pandoc-wrapper.sh` tool will use `expand(1)` to expand
leading ASCII TAB characters into multiples of 8 ASCII space
characters on all markdown data before piping it into `pandoc(1)`.
Thus, any leading ASCII TAB character in markdown files will be
automatically converted into spaces using 8 character tabs.

Changed `bin/pandoc-wrapper.sh` VERSION from "1.6.3 2024-06-22"
to "1.7 2024-06-22" to preform the above.

Perform `make www` to perform the above and test under macOS.

It turns out that only one other HTML file was impacted: `bugs.html`.
All other leading ASCII tab characters have been rendered
[Mostly Harmless](https://en.wikipedia.org/wiki/Mostly_Harmless).  :)

bugs.html

@@ -960,7 +960,7 @@ test the entry one can do:</p>
 sentence.</p>
 <p>But doing this shows instead:</p>
 <pre><code>    echo &quot;Quartz glyph jocks vend, fix, BMW.&quot; | compress | ./btoa | ./jaw
-    a얖?)V...?????777??hC??h??-? )SSSSXXX????r?L=???*?-???ppp,,,?R
+    a얖?)V...?????777??hC??h??-?        )SSSSXXX????r?L=???*?-???ppp,,,?R
     ?j
     111-)))? &#39;..F@E
                    ???b111?