Update README.md

Author: AntonEvmenenko

README.md

@@ -23,6 +23,6 @@ This is the C++ & SDL2 port of Gravity Defied, which includes all the features o
 
 For more information, please visit official site of Codebrew Software: [codebrew.se](http://codebrew.se)
 
-### Contributing
+# Contributing
 
 If you want to contribute, feel free to discuss your idea with the rest of the developers in our [Telegram group](https://t.me/+sOfxjrsbkbEwNzc6)