Read pre-compressed gzip files

services/nginx/conf.d/qaboard.conf

@@ -59,6 +59,13 @@ server {
     autoindex on;
     access_log off;
     include cors;
+    # let users save precompressed $file.gz
+    # using "gzip $file" or https://github.com/google/zopfli
+    gzip_static  on;
+    # https://stackoverflow.com/questions/33375304/what-are-the-options-for-the-gzip-proxied-directive-for
+    # gzip_proxied expired no-cache no-store private auth;
+    # for clients that don't support gzip if only that version is available
+    gunzip       on;
   }
 
   # IIIF Cantaloupe Server