chore: fixed format of pr template; added sections

Note: this is using the updated PR template

Description/Contribution Summary

Updated PR template. Fixes #40

Updated PR template to add formatting, remove unnecessary YAML pre-amble, and add specific sections.

[X] 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)

No changes to page content, only pull_request_template.md

Small PR - review of .github/pull_request_template.md only

[X] I have read the CONTRIBUTING.md guidance for raising pull requests
[X] I have followed the intended structure of this project
[X] I have performed a self-review
[X] I have used comments, particularly in hard-to-understand areas
[X] This pull-request meets the accessibility guidance provided in the contributing guidance.
[X] My changes generate no new warnings

None