Create instructions for serving static files from reverse proxy

[mstahv]

Serving static files (like the generated front-end bundle) directly from reverse proxy or from a server designed primarily for serving files is faster and saves resources from the actual application server to more meaningful actions. This can be meaningful especially if a lot of users enter the application at the same time (and they will all request a "number of files").

This page could have a section for it:

https://vaadin.com/docs/latest/flow/production/reverse-proxy

In most simplest form we could just list which files from the artifact to move to apache/nginx/... or we could even provide an example buildstep as a basis for deployment automation (copies relevant files).

Listing "static content" would also help people to configure modern "smart proxies" (clouldflare etc) so that they could event geo-loadbalance those.

[mstahv]

I made a poc by coping files to nginx and by putting try_files in front of the proxy config (@ backend here):

location / {
    try_files $uri @backend;
}