[Feature Request] Get installer to add `PATH` modification codes to .bashrc

[Crispy13]

Hi.

For a specific reason, I need to install rust without internet access.
The system is Linux. I extracted tar ball and run install.sh.

When I installed rust with rustup, it automatically added some PATH modification code to my .bashrc.

But if I'm not wrong, install.sh seems not to do that.

Could you add the codes to it?

Also, Could you add some description about local install (--prefix=~/.cargo) in the other installation method documentation?
Or I think it would be good that install.sh installs rust like rustup. (default on local, don't need sudo permission)