## Changes
1. Add a Why section to the pull request template
2. Slightly improve language in the existing sections
## Why
Providing the right context for the reviewer in the PR description is
important as it usually cannot be inferred from the code itself. The new
section directly prompts the requester to provide such context
## Tests
Checked that the markdown is still rendered correctly in the local
viewer
## Changes
<!-- Summary of your changes that are easy to understand -->
Add PR template to bring structure to PRs.
## Tests
<!-- How is this tested? -->
Copy pasted template in this description to check how it looks.
Template working in VSCode repository
## Public Tickets
<!--
Link to public tickets (if any). Please don't mention internal tickets.
-->
N/A