Update README.md

Added coding-competitions.md link.

Author: sidtr0

README.md

@@ -9,3 +9,4 @@ If you are starting out and want to follow a curriculum for CS, you can check ou
 ## Table of contents
 1. [Books](./books.md)
 2. [Project ideas](./ideas.md)
+3. [Coding competetions](./coding-competetions.md)