Add CONTRIBUTING.md

Issue bvschaik#73

Author: bvschaik

CONTRIBUTING.md

@@ -0,0 +1,10 @@
+# Contributing
+
+When contributing to this repository, please first discuss the change you wish to make via issue,
+Gitter, or any other method with the owner of this repository before opening a pull request.
+
+## Aim of the project
+
+The aim of Julius is to re-create the exact same logic that the original Caesar 3 uses, with full savegame compatibility, but with user interface enhancements, like widescreen support. The same logic also means that any gameplay bugs present in Caesar 3 will also be present in Julius, like the 100-year-old ghosts.
+
+Later on there may be an 'enhanced' edition with new features, but for now any pull requests which change the game logic will be declined.