Updates sitemap.xml for havana release links

Adds an XSLT that transforms a generated sitemap, removing folsom
and trunk links

backport: stable/havana

Change-Id: I4484d50fa60eb53e3155fe4e119c30e54b03832e
Partial-bug: 1191447

sitemap/transform-sitemap.xslt

@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+<!-- Use this transform on a sitemap.xml file generated from freesitemapgenerator.com -->
+<!-- It removes the /trunk URLs and the release URLs that you indicate below, here it's folsom -->
+<xsl:stylesheet version="1.0"
+    xmlns:sm="http://www.sitemaps.org/schemas/sitemap/0.9"
+    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
+    
+    <!-- template match equals any other url element, keep -->
+    <xsl:template match="node() | @*">
+        <xsl:copy>
+            <xsl:apply-templates select="node() | @*"/>
+        </xsl:copy>
+    </xsl:template>
+    
+    <!-- discard any url/loc that refer to trunk or folsom -->
+    <xsl:template match="sm:url[starts-with(./sm:loc,'http://docs.openstack.org/trunk')]"/>
+    <xsl:template match="sm:url[starts-with(./sm:loc,'http://docs.openstack.org/folsom')]"/>
+    
+</xsl:stylesheet>