Add module metadata to generated sitemaps

src/SitemapGenerator.php

@@ -13,6 +13,7 @@ class SitemapGenerator {
   const ENCODING = 'UTF-8';
   const XMLNS = 'http://www.sitemaps.org/schemas/sitemap/0.9';
   const XMLNS_XHTML = 'http://www.w3.org/1999/xhtml';
+  const GENERATED_BY = 'Generated by the Simple XML sitemap Drupal module: https://drupal.org/project/simple_sitemap.';
 
   private $generator;
   private $db;
@@ -137,6 +138,7 @@ class SitemapGenerator {
     $writer->openMemory();
     $writer->setIndent(TRUE);
     $writer->startDocument(self::XML_VERSION, self::ENCODING);
+    $writer->writeComment(self::GENERATED_BY);
     $writer->startElement('sitemapindex');
     $writer->writeAttribute('xmlns', self::XMLNS);
 
@@ -166,6 +168,7 @@ class SitemapGenerator {
     $writer->openMemory();
     $writer->setIndent(TRUE);
     $writer->startDocument(self::XML_VERSION, self::ENCODING);
+    $writer->writeComment(self::GENERATED_BY);
     $writer->startElement('urlset');
     $writer->writeAttribute('xmlns', self::XMLNS);
     $writer->writeAttribute('xmlns:xhtml', self::XMLNS_XHTML);