Add Contributing file

CONTRIBUTING.md

@@ -0,0 +1,30 @@
+## How to contribute to TF Tabular
+
+#### **Did you find a bug?**
+
+* **Ensure the bug was not already reported** by searching on GitHub under [Issues](https://github.com/xmartlabs/tf_tabular/issues).
+
+* If you're unable to find an open issue addressing the problem, [open a new one](https://github.com/xmartlabs/tf_tabular/issues/new). Be sure to include a **title and clear description**, as much relevant information as possible, and a **code sample** or an **executable test case** demonstrating the expected behavior that is not occurring.
+
+#### **Did you write a patch that fixes a bug?**
+
+* Open a new GitHub pull request with the patch.
+
+* Ensure the PR description clearly describes the problem and solution. Include the relevant issue number if applicable.
+
+#### **Do you intend to add a new feature or change an existing one?**
+
+* Open a discussion and gather feedback about the feature you want to add or the change you want to make.
+Meanwhile you can start working on the code.
+
+* Once you have positive feedback, open a pull request with the new feature or change.
+
+<!-- #### **Do you have questions about the source code?** -->
+
+<!-- #### **Do you want to contribute to the documentation?** -->
+
+---------
+
+Thanks for contributing!
+
+Xmartlabs Team