ops: add pr template

.github/pull_request_template.md

@@ -0,0 +1,22 @@
+<!--- Thank you for contributing to xtxf! -->
+
+## Description
+
+<!--- Describe your changes -->
+
+## Motivation
+
+<!--- Why is this change required? What problem does it solve? -->
+<!--- If it fixes an open issue, insert the link to an issue here. -->
+
+## Testing
+
+<!--- Describe how you tested your changes. -->
+
+## Checklist:
+
+<!--- Go over all the following points and put an `x` in all the boxes that apply. -->
+
+- [ ] My code follows the code style of this project.
+- [ ] I have updated the documentation accordingly.
+- [ ] I have added tests to cover my changes.