Update broken link for contributing to Sway in README.md
Closes
@@ -49,4 +49,4 @@ cargo run --bin forc -- --help
We welcome contributions to Sway!
-Please see the [Contributing To Sway](https://fuellabs.github.io/sway/latest/reference/contributing_to_sway.html) section of the Sway book for guidelines and instructions to help you get started.
+Please see the [Contributing To Sway](https://fuellabs.github.io/sway/master/reference/contributing_to_sway.html) section of the Sway book for guidelines and instructions to help you get started.
