Create CONTRIBUTING.md (#205)

CONTRIBUTING.md

@@ -0,0 +1,13 @@
+# Contribution Guide
+
+Thank you for contributing to the repository! Have fun coding and meeting new friends!
+
+### Instructions
+Master branch is protected, impossible to push there without making a Pull Request.
+There are two ways to contribute to the repository:
+- fork the repository on GitHub, write your code on the fork, then open a Pull Request to the original repository; our maintainers will review and merge the edits;
+- or, join our Discord Server (link below) and ask our maintainer arthuro555 to add you to the organization in GitHub, so you can push to any branch, other than `master`.
+
+Easy, and simple!
+
+Here's a link to our Discord Server: https://discord.gg/7fZHdqaJQC