Re: doc: add missing "id" attributes to extension packaging page

This is for the committer, as an FYI.

I cut out the <xsl:template name="section.heading"> portion
of the docbook XSLT and diffed it with the code for the
same template in the patch.  The diff looks like:

-- /tmp/sections.xsl    2023-03-22 13:00:33.432968357 -0500
+++ /tmp/make_html_ids_discoverable_v3.patch    2023-03-22 13:03:39.776930603 -0500
@@ -52,5 +52,8 @@
       </xsl:call-template>
     </xsl:if>
     <xsl:copy-of select="$title"/>
+    <xsl:call-template name="pg.id.link">
+      <xsl:with-param name="object" select="$section"/>
+    </xsl:call-template>
   </xsl:element>
 </xsl:template>

(So, this output would start with line 52 of the template,
not from the top of the stock sections.xsl file.)

However, I am not really familiar with exactly what flavor
of docbook, version, namespace-d or not, etc., that PG
uses.  So I could be diffing with the wrong thing.

Hope this helps and is not just noise.

Regards,

Karl <kop@karlpinc.com>
Free Software:  "You don't pay back, you pay forward."
                 -- Robert A. Heinlein