Add documentation and test updates to pull request template

[yemeen]

updates this template to include more general changes

closes #44

<!--- Provide a general summary of your changes in the Title above -->

## Description
<!--- Describe your changes in detail -->

## Motivation and Context
<!--- Why is this change required? What problem does it solve? -->
<!--- If it fixes an open issue, please link to the issue here. -->

## How has this been tested?
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<!--- Include details of unit tests added, tests ran to see how -->
<!--- your change affects other areas of the code, etc. -->

## Types of changes
<!--- What types of changes does your code introduce? Put an `x` in all the boxes that apply: -->
- [ ] 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
<!--- Go over all the following points, and put an `x` in all the boxes that apply. -->
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- [ ] My code follows the code style of this project. (`make clean`)
- [ ] I have incremented the version number in the `pyproject.toml` file.
- [ ] I have added tests to cover my changes.
- [ ] All new and existing tests passed. (`make tests`)