Add donation links (GitHub Sponsors, Ko-fi)

README.md

@@ -1,3 +1,8 @@
 # rimworld-foulplay-wiki
 
-Public wiki for Foul Play (source is private).
+Public wiki for Foul Play (source is private).
+
+## Support
+
+If you enjoy Foul Play, consider supporting development via
+[GitHub Sponsors](https://github.com/sponsors/sudolulo) or [Ko-fi](https://ko-fi.com/sudolulo).