Update comment

petere · petere · commit 254361cf1aec · 2024-02-08T10:22:42.000+01:00
The documentation output format htmlhelp is no longer supported, but a
comment still mentioned it.
diff --git a/doc/src/sgml/stylesheet-common.xsl b/doc/src/sgml/stylesheet-common.xsl
@@ -4,7 +4,7 @@
 
 <!--
   This file contains XSLT stylesheet customizations that are common to
-  all output formats (HTML, HTML Help, XSL-FO, etc.).
+  all output formats (HTML, XSL-FO, man, etc.).
   -->
 
 <xsl:include href="stylesheet-speedup-common.xsl" />
