rustup-cli: Fix some formatting which got missed
rustup-cli: Fix some formatting which got missed

A recent PR about documentation missed some formatting.  This
fixes that by dint of a simple `cargo fmt`.

Signed-off-by: Daniel Silverstone <3cc17a76d780e0cd3d87bad586a1c53967be5625@digital-scurf.org>

rust-lang/rustup,inejge/rustup.rs,inejge/rustup.rs,inejge/rustup.rs,inejge/rustup.rs,inejge/rustup.rs,nodakai/rustup.rs,rust-lang/rustup,nodakai/rustup.rs,nodakai/rustup.rs,rust-lang/rustup,nodakai/rustup.rs,rust-lang/rustup,rust-lang/rustup,nodakai/rustup.rs