add a pull request template

Created by: deepakduggirala

This template provides guidelines and instructions for creating pull requests. It helps with maintaining consistency in change descriptions which makes it easier for maintainers and reviewers to understand the purpose and scope of the changes. They can act as needed documentation and its checklists ensure developers completed all necessary steps before submitting a PR.

Please feel free to edit this template to suit our team's needs.

https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/creating-a-pull-request-template-for-your-repository