Relog advice is now shell restart advice

Restarting the shell is now enough. Relogging restarts the shell so we don't need to suggest relogging.

Author: Gurkenglas

doc/src/faq.md

@@ -39,5 +39,5 @@ closing your editor) and try again.
 
 ### rustup exited successfully but I can't run `rustc --version`
 
-Restart your shell, or log out and back in. This will reload your `PATH` environment
+Restart your shell. This will reload your `PATH` environment
 variable to include Cargo's bin directory (`$CARGO_HOME/bin`).

src/cli/self_update.rs

@@ -162,7 +162,7 @@ macro_rules! post_install_msg_unix {
     () => {
         r"# Rust is installed now. Great!
 
-To get started you may need to log out and back in.
+To get started you may need to restart your current shell.
 This would reload your `PATH` environment variable to include
 Cargo's bin directory ({cargo_home}/bin).