sync max body size (#3334)

While setting up a qiita instance, we stumbled upon issues when uploaded files. File < chunk size were not affected. Also, this error only occurred when qiita run within the nginx setup, not as pure python instance. It looks like there is a default maximum body size for GET commands of 1M in nginx. Therefore, you might want to increase this size in the `nginx_example.conf` or at least leave a comment to inform others.

qiita_pet/nginx_example.conf

@@ -3,6 +3,8 @@ events {
 }
 
 http {
+    client_max_body_size 4M;  # increase maximum body size from default 1M to match https://github.com/qiita-spots/qiita/blob/ac62aba5333f537c32e213855edc39c273aa9871/qiita_pet/static/vendor/js/resumable-uploader.js#L51
+
     # ports to redirect for mainqiita
     upstream mainqiita {
         server localhost:21174;