Instructions for updating icons are incomplete

[nazar-pc]

> cargo run
thread 'main' panicked at update_icons/src/icon_list.rs:22:65:
called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }

Instructions on updating submodules are missing, I don't use them often and have no idea how to bypass update = none, am I supposed to edit the file?

Also having both main.rs and bin/update_icons.rs is equally confusing.

[AaronErhardt]

This does the trick:

git submodule update --remote --checkout

[nazar-pc]

Yes, that works. Consider adding to readme 🙂