doc: add documentation for brotli support

Backport-PR-URL: https://github.com/nodejs/node/pull/27681
PR-URL: https://github.com/nodejs/node/pull/24938


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>