Apply suggestions from code review

Co-authored-by: Joshua Nelson <[email protected]>

Author: guswynn

src/building/suggested.md

@@ -80,9 +80,11 @@ rustup override set nightly
 after [installing a nightly toolchain] with `rustup`. Don't forget to do this for all
 directories you have [setup a worktree for].
 
-**note** see [the section on vscode] for how to configure it with this real rustfmt `x.py` uses, 
+**Note** see [the section on vscode] for how to configure it with this real rustfmt `x.py` uses, 
 and [the section on rustup] for how to setup `rustup` toolchain for your bootstrapped compiler
 
+**Note** This does _not_ allow you to build `rustc` with cargo directly. You still have to use `x.py` to work on the compiler or standard library, this just lets you use `cargo fmt`.
+
 [installing a nightly toolchain]: https://rust-lang.github.io/rustup/concepts/channels.html?highlight=nightl#working-with-nightly-rust
 [setup a worktree for]: ./suggested.html#working-on-multiple-branches-at-the-same-time
 [the section on vscode]: suggested.html#configuring-rust-analyzer-for-rustc