docs: mention client_max_body_size affects LFS (go-gitea#18291)

Author: jtojnar

docs/content/doc/usage/reverse-proxies.en-us.md

@@ -128,6 +128,7 @@ This error indicates nginx is configured to restrict the file upload size.
 
 In your nginx config file containing your Gitea proxy directive, find the `location { ... }` block for Gitea and add the line
 `client_max_body_size 16M;` to set this limit to 16 megabytes or any other number of choice.
+If you use Git LFS, this will also limit the size of the largest file you will be able to push.
 
 
 ## Apache HTTPD