fix blob support in example config

docs/example.nginx.conf

@@ -154,7 +154,23 @@ server {
 
     # encrypted blobs are immutable and are thus cached for a year
     location ^~ /blob/ {
+        if ($request_method = 'OPTIONS') {
+            add_header 'Access-Control-Allow-Origin' '*';
+            add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
+            add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Conten
+t-Type,Content-Range,Range';
+            add_header 'Access-Control-Max-Age' 1728000;
+            add_header 'Content-Type' 'application/octet-stream; charset=utf-8';
+            add_header 'Content-Length' 0;
+            return 204;
+        }
         add_header Cache-Control max-age=31536000;
+        add_header 'Access-Control-Allow-Origin' '*';
+        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
+        add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Ty
+pe,Content-Range,Range';
+        add_header 'Access-Control-Expose-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-T
+ype,Content-Range,Range';
         try_files $uri =404;
     }