* added comment for pillar example

* removed override releasever variable use for CentOS

nginx/ng/install.sls

     - name: nginx
     - humanname: nginx repo
     {%- if salt['grains.get']('os') == 'CentOS' %}
-    - baseurl: 'http://nginx.org/packages/centos/{{ nginx.lookup.rh_os_releasever }}/$basearch/'
+    - baseurl: 'http://nginx.org/packages/centos/$releasever/$basearch/'
     {%- else %}
     - baseurl: 'http://nginx.org/packages/rhel/{{ nginx.lookup.rh_os_releasever }}/$basearch/'
     {%- endif %}

pillar.example

       vhost_available: /etc/nginx/sites-available
       vhost_enabled: /etc/nginx/sites-enabled
       vhost_use_symlink: True
+      # This is required for RedHat like distros (Amazon Linux) that don't follow semantic versioning for $releasever
       rh_os_releasever: '6'
 
     # Source compilation is not currently a part of nginx.ng