Provide a guideline for contributing code

CONTRIBUTING.md

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+# How to contribute
+
+We are really glad you're reading this, because we need volunteer developers to help this project improve.
+
+If you haven't already, come find us in [Discord](https://discord.gg/wvesC6). We want you working on things you're excited about, and we can give you instant feedback.
+
+## Testing
+
+We have a handful of unit tests, but most of our testbed consists of running it with existing projects. 
+Try our builds and pull requests in your own projects and let us know how it goes.
+
+## Submitting changes
+
+Please send a [GitHub Pull Request](https://github.com/vis2k/HLAPI-Community-Edition/pull/new/improvements) with a clear list of what you've done (read more about [pull requests](http://help.github.com/pull-requests/)). 
+When you send a pull request, we will love you forever if you include unit tests. 
+We can always use more test coverage. 
+Please follow our coding conventions (below) and make sure all of your commits are atomic (one feature per commit). Rebase your pull requests if necessary.
+
+Always write a clear log message for your commits. One-line messages are fine for small changes, but bigger changes should look like this:
+
+    $ git commit -m "A brief summary of the commit
+    > 
+    > A paragraph describing what changed and its impact."
+    
+Submit your pull requests to the right branch:
+  * fixes for bug fixes 
+  * improvements for refactorings and cleanups,  we love to delete code.
+  * features for new shiny features you want in HLAPI.
+  
+If your pull request breaks any test,  it has no hope of being merged.
+
+## Coding conventions
+
+Start reading our code and you'll get the hang of it. We optimize for readability:
+
+  * We indent using 4 spaces (soft tabs)
+  * We value simplicity. The code should be easy to read and avoid magic
+  * We use default visual studio code formatting standard
+  * This is open source software. Consider the people who will read your code, and make it look nice for them. It's sort of like driving a car: Perhaps you love doing donuts when you're alone, but with passengers the goal is to make the ride as smooth as possible.
+ 
+Thanks.