Added NGINX variables index.

Author: y82

content/nginx/variables.md

@@ -0,0 +1,7 @@
+---
+title: NGINX Variables Index
+url: /nginx/variables
+weight: 800
+---
+
+<!-- this is dummy doc is used to create a list page entry that redirects users to the variables index in the .org docs. The redirect is configured in netlify.toml -->