Increase client_max_body_size to 100M in Nginx config example

Nginx has a default limit of 1MB on the size of the request body. This
is too small in most cases. This commit increases it to 100M that can
cover most cases.

docs/web_deployment.pod

@@ -195,6 +195,8 @@ With the nginx configuration:
         access_log  /var/log/nginx/access.log;
 
         location / {
+            client_max_body_size 100M;
+
             fastcgi_param  QUERY_STRING       $query_string;
             fastcgi_param  REQUEST_METHOD     $request_method;
             fastcgi_param  CONTENT_TYPE       $content_type;