PR #77 follow-up: Document nginx_log_format variable.

README.md

@@ -104,6 +104,13 @@ Extra lines to be inserted in the top-level `http` block in `nginx.conf`. The va
       proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
       proxy_set_header   Host $http_host;
 
+    nginx_log_format: |
+      '$remote_addr - $remote_user [$time_local] "$request" '
+      '$status $body_bytes_sent "$http_referer" '
+      '"$http_user_agent" "$http_x_forwarded_for"'
+
+Configures Nginx's [`log_format`](http://nginx.org/en/docs/http/ngx_http_log_module.html#log_format). options.
+
     nginx_default_release: ""
 
 (For Debian/Ubuntu only) Allows you to set a different repository for the installation of Nginx. As an example, if you are running Debian's wheezy release, and want to get a newer version of Nginx, you can install the `wheezy-backports` repository and set that value here, and Ansible will use that as the `-t` option while installing Nginx.

defaults/main.yml

@@ -73,6 +73,7 @@ nginx_upstreams: []
 #     "srv2.example.com weight=3",
 #     "srv3.example.com"
 #   }
+
 nginx_log_format: |
   '$remote_addr - $remote_user [$time_local] "$request" '
   '$status $body_bytes_sent "$http_referer" '