Update wordpress crawler for new sitemap.

[charvolant]

Wordpress now has multiple sources of site information, eg.

https://www-test.ala.org.au/sitemap-files/xml/posts/page/1/index.xml https://www-test.ala.org.au/sitemap-files/xml/posts/post/1/index.xml

This will be needed before re-deploying the bie-index.

[adam-collins]

This is resolved by the use of the parent index https://www.ala.org.au/xmlsitemap.xml