add a note regarding macos xcode dev tools
@@ -22,6 +22,8 @@ git clone https://github.com/rust-lang/rustlings.git
cd rustlings
```
+_Note: If you're on MacOS, make sure you've installed Xcode and its developer tools by typing `xcode-select --install`._
+
Once in the directory you can install `rustlings` on your machine and run the introduction:
```bash
