[AssetMapper] Recommend `Cache-Control` instead of `Expires` HTTP header?

[ThomasLandauer]

@weaverryan Is there a specific reason why you're recommending to set Expires and not Cache-Control at https://symfony.com/doc/current/frontend/asset_mapper.html#optimizing-performance ?

According to https://stackoverflow.com/q/5799906/1668200 Cache-Control is something like the "successor" of Expires. And Lighthouse is only mentioning Cache-Control: https://developer.chrome.com/docs/lighthouse/performance/uses-long-cache-ttl?utm_source=lighthouse&utm_medium=devtools#how_to_cache_static_resources_using_http_caching

So what do you think about changing the recommendation to Cache-Control?

[smnandre]

I think we should use both. The word expires is really self)explanatory for newcomers (in a functional way i mean), but you're absolutely right, when we speak implementation / RFC, we should do it using "Cache-Control", as it superseeds Expires entirely !

[ThomasLandauer]

OK, see #19628 - I squeezed the word "expiry" in :-)