Merge pull request tensorflow#18759 from filipefilardi/master

Add Pull Request Template

Author: martinwicke

CONTRIBUTING.md

@@ -1,5 +1,16 @@
 # Contributing guidelines
 
+## Pull Request Checklist
+
+Before sending your pull requests, make sure you followed this list.
+
+- Read [contributing guidelines](CONTRIBUTING.md).
+- Read [Code of Conduct](CODE_OF_CONDUCT.md).
+- Ensure you have signed the [Contributor License Agreement (CLA)](https://cla.developers.google.com/).
+- Check if my changes are consistent with the [guidelines](https://github.com/tensorflow/tensorflow/blob/master/CONTRIBUTING.md#general-guidelines-and-philosophy-for-contribution).
+- Changes are consistent with the [Coding Style](https://github.com/tensorflow/tensorflow/blob/master/CONTRIBUTING.md#c-coding-style).
+- Run [Unit Tests](https://github.com/tensorflow/tensorflow/blob/master/CONTRIBUTING.md#running-unit-tests).
+
 ## How to become a contributor and submit your own code
 
 ### Contributor License Agreements