Set sitemap file name to sitemap.xml

This is consistent with the current filename on production
This will later be renamed to sitemap_tech_guides.xml

Author: nmelehan-akamai

config.toml

@@ -18,7 +18,7 @@ disqusShortname="linode-1"
 enableGitInfo = true
 
 [sitemap]
-filename = "sitemap_linodedocs.xml"
+filename = "sitemap.xml"
 
 [outputs]
 home = ["HTML", "RSS"]