`elan toolchain help link` message uses the term "crate"

[simon-dima]

This is most likely left over from when elan was forked from rustup: https://github.com/leanprover/elan/blob/58e8d545e33641f66dbcbd22c4283109e71757be/src/elan-cli/help.rs#L61-L62 The help message should be modified to use Lake's terms, I believe "package" would be correct here.