add contributors in README.md

Hello everyone!

I added the contributors in the readme.md file in the repository: viliusle/miniPaint. I would like to contribute to this pull-request and I hope you all accept it.

what do you all think of this idea?

README.md

@@ -51,6 +51,11 @@ See [Wiki > Build instructions](https://github.com/viliusle/miniPaint/wiki/Build
 ## Wiki
 See [Wiki](https://github.com/viliusle/miniPaint/wiki)
 
+## Contributors
+<a align="center" href="https://github.com/viliusle/miniPaint/graphs/contributors">
+ <img src="https://contrib.rocks/image?repo=viliusle/miniPaint" />
+</a>
+
 ## License
 MIT License