Update building_from_source.md

[stefnotch]

See denoland/deno#27535

Should I reproduce their installation instructions in this file as well?

[lucacasonato]

This can’t be right - Deno does not depend on libuv. @littledivy or @devsnek: what is it used for?

[dsherret]

@lucacasonato it's here: https://github.com/nathanwhit/libuv-sys-lite/blob/a9de9aace3d22f9784141a59f8ec0613085ed764/crate/Cargo.toml#L24

[nathanwhit]

it's just for tests, let me see if I can drop the dep