Chore: Add pull request template

[dblodorn]

Example PR template added to .github directory on root level.

Title: PULL_REQUEST_TEMPLATE.md

---

Description

Motivation and Context

How has this been tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• Does your submission pass tests?

Breaking Changes:

New features: