Add config-template

doc/docca/include/docca/doxygen.xsl

@@ -10,6 +10,8 @@
   file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 -->
 
+<!-- CONFIG_TEMPLATE -->
+
 <xsl:output method="text"/>
 <xsl:strip-space elements="*"/>
 <xsl:preserve-space elements="para"/>