Clarifying "How to test HTTP/3 in browsers"

[hwsamuel]

As of the time of writing this, Firefox also has a Boolean config alt-svc-mapping-for-testing in addition to the network.http.http3.alt-svc-mapping-for-testing setting. It is unclear if the Boolean setting needs to be enabled to true for the http3 setting to work.

[kelmenhorst]

Thanks for bringing this up, I wasn't aware. What Firefox version are you using?

[hwsamuel]

I'm using 119.0 (64-bit Flatpak version) on Ubuntu 22.04