update nginx.sample.conf to take attachmetns into account

config/nginx.sample.conf

@@ -21,8 +21,8 @@ server {
   location / {
     root /home/discourse/discourse/public;
 
-    ## optional image anti-hotlinking rules
-    #location ~ \.(jpe?g|png|gif)$ {
+    ## optional upload anti-hotlinking rules
+    #location ~ ^/uploads/ {
     #  valid_referers none blocked mysite.com *.mysite.com;
     #  if ($invalid_referer) {
     #    return 403;
@@ -35,7 +35,7 @@ server {
       add_header ETag "";
     }
 
-    location ~ ^/assets/ {
+    location ~ ^/(assets|uploads)/ {
       expires 1y;
       add_header Cache-Control public;
       add_header ETag "";