Add docsearch:page_rank attribute

Author: osfameron

src/partials/head-meta.hbs

@@ -75,6 +75,7 @@
 <meta name="docsearch:version_rank" content="{{page.attributes.version-rank}}">
 <meta name="docsearch:status" content="{{page.attributes.status}}">
 <meta name="docsearch:edition" content="{{page.attributes.edition}}">
+<meta name="docsearch:page_rank" content="{{page.attributes.page_rank}}">
 
 
 {{#with page.attributes.meta-zd-site-verification}}