MYSY2 -> MSYS2

Author: saschanaz

README.md

@@ -73,7 +73,7 @@ Read ["Installing Rust"] from [The Book].
    ```
 
 3. Run `mingw32_shell.bat` or `mingw64_shell.bat` from wherever you installed
-   MYSY2 (i.e. `C:\msys`), depending on whether you want 32-bit or 64-bit Rust.
+   MSYS2 (i.e. `C:\msys`), depending on whether you want 32-bit or 64-bit Rust.
 
 4. Navigate to Rust's source code, configure and build it: