Fix generation of ./INSTALL for the distribution tarball

"make dist", in charge of creating a distribution tarball, failed when
attempting to generate ./INSTALL as a new reference added to
guc-default-toast-compression on the documentation for the installation
details was not getting translated properly to plain text.  Like all the
other link references on this page, this adds a new entry to
standalone-profile.xsl to allow the generation of ./INSTALL to finish
properly.

Oversight in 02a93e7e, per buildfarm member guaibasaurus.

doc/src/sgml/standalone-profile.xsl

@@ -48,6 +48,10 @@ variant without links and references to the main documentation.
   <xsl:text>the documentation</xsl:text>
 </xsl:template>
 
+<xsl:template match="xref[@linkend='guc-default-toast-compression']">
+  <xsl:text>the configuration parameter default_toast_compression</xsl:text>
+</xsl:template>
+
 <xsl:template match="xref[@linkend='install-windows']">
   <xsl:text>the documentation</xsl:text>
 </xsl:template>