reword toolchains instructions

Signed-off-by: Dmitry S <[email protected]>

docs/book/aya/crosscompile.md

@@ -9,7 +9,7 @@ to add instructions to do that soon (PRs welcome!).
 Cross compilation should work on both Intel and Apple Silicon Macs.
 
 1. Install `rustup` following the instructions on <https://rustup.rs/>
-1. Install a rust stable and nightly toolchains:
+1. Install the stable and nightly rust toolchains:
 ```bash
 rustup install stable
 rustup toolchain install nightly --component rust-src
@@ -26,7 +26,7 @@ brew install llvm
 
 1. Install the musl cross compiler:
 ```bash
-brew install FiloSottile/musl-cross/musl-cross`
+brew install FiloSottile/musl-cross/musl-cross
 ```
 See [homebrew-musl-cross](https://github.com/FiloSottile/homebrew-musl-cross)
 for platform-specific options.