add Contributing file. Resolve #93

CONTRIBUTING.md

@@ -0,0 +1,12 @@
+Thanks for your interest on contributing to this repo
+=====================================================
+
+To keep things simple and organized, we need to keep some basic rules when adding new links:
+
+1 - Make sure the link you are adding is not already added
+2 - Make sure the link is relevant to this repo. We are focusing on game development here.
+3 - Make sure the list you are adding is kept alphabetically ordered. This make it easier to find the links
+4 - Be nice, be cool, and we will always love you!
+
+
+:)