give nginx config default max upload size

docker/nginx/root/docker/templates/etc/nginx/conf.d/default.conf

@@ -14,7 +14,7 @@ server {
     index index.html index.htm index.php;
 
     charset utf-8;
-    client_max_body_size {{ getenv "POST_MAX_SIZE" }};
+    client_max_body_size {{ getenv "POST_MAX_SIZE" "61M" }};
 
     location / {
         try_files $uri $uri/ /index.php?$query_string;