Mention code style in readme (#1047)

* Add note on code style to readme

* Fix readme section numbering and rebuild table of contents

README.md

@@ -8,11 +8,12 @@ An open source re-implementation of Chris Sawyer's Locomotion. A construction an
 # Contents
 - 1 - [Introduction](#1-introduction)
 - 2 - [Downloading the game (pre-built)](#2-downloading-the-game-pre-built)
-- 3 - [Building the game](#3-building-the-game)
-  - 3.1 - [Building prerequisites](#31-building-prerequisites)
-  - 3.2 - [Compiling and running](#32-compiling-and-running)
-- 4 - [Licence](#4-licence)
-- 5 - [More information](#5-more-information)
+- 3 - [Contributing](#3-contributing)
+- 4 - [Compiling the game](#4-compiling-the-game)
+  - 4.1 - [Building prerequisites](#41-building-prerequisites)
+  - 4.2 - [Compiling and running](#42-compiling-and-running)
+- 5 - [Licence](#5-licence)
+- 6 - [More information](#6-more-information)
 
 ---
 
@@ -53,6 +54,9 @@ It can be bought at e.g. [Steam](https://store.steampowered.com/app/356430/) or
 We warmly welcome any contributions to the project, e.g. for C++ code (game implementation, bug fixes, features) or localisation (new translations).
 Please have a look at our [issues for newcomers](https://github.com/OpenLoco/OpenLoco/labels/good%20first%20issue).
 
+For code contributions, please stick to our [code style](https://github.com/OpenLoco/OpenLoco/wiki/Coding-Style).
+You can use `clang-format` to apply these guidelines automatically.
+
 ---
 
 # 4 Compiling the game
@@ -116,7 +120,7 @@ cp -r ../data ./data
 
 ---
 
-# 5 More information
+# 6 More information
 - [GitHub](https://github.com/OpenLoco/OpenLoco)
 - [TT-Forums](https://www.tt-forums.net)
 - [Locomotion subreddit](https://www.reddit.com/r/locomotion/)