Merge #316

316: Update index.md r=jamesmunns a=lyrakisk

Fix typo

Co-authored-by: Konstantinos Lyrakis <24938740+lyrakisk@users.noreply.github.com>

Author: bors[bot]

src/intro/index.md

@@ -18,7 +18,7 @@ The goals of this book are:
   How to best use Rust language features to write more correct embedded
   software.
 
-* Serve as a cookbook in some cases. e.g. How do I do mix C and Rust in a single
+* Serve as a cookbook in some cases. e.g. How do I mix C and Rust in a single
   project?
 
 This book tries to be as general as possible but to make things easier for both