Add a PR template

[haani-niyaz]

Include a PR template so we have consistent process to describe the PR and include what we would generally expect to be done before raising the PR.

A sample template has been added below.

As per https://github.com/rog-golang-buddies/golang-template-repository/wiki/Platform-Team-Onboarding-Guide use github as the commit scope.

Example

## Description

_Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change._

Fixes # (issue)

## Type of change

Please delete options that are not relevant.

- [ ] 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)
- [ ] This change requires a documentation update

## How Has This Been Tested?

_Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration_

## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my own code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation
- [ ] I have checked my code/docs and corrected any misspellings