message: chore: update PR template
  (Follow-up to team discussion) Modify PR template to remind PR creators to state the motivation for their changes. This will help reviewers understand the context and reasoning behind the PR.
diff: -#### Description of changes
  +#### Details
  -<!--
  - A great PR description includes:
  - * A high level overview (usually a sentence or two) describing what the PR changes
  - * What is the motivation for the change? This can be as simple as "addresses issue #123"
  - * Were there any alternative approaches you considered? What tradeoffs did you consider?
  - * What **doesn't** the change try to do? Are there any parts that you've intentionally left out-of-scope for a later PR to handle? What are the issues/work items tracking that later work?
  - * Is there any other context that reviewers should consider? For example, other related issues/PRs, or any particularly tricky/subtle bits of implementation that need closer-than-normal review?
  --->
  +<!-- Usually a sentence or two describing what the PR changes -->
  +
  +##### Motivation
  +
  +<!-- This can be as simple as "addresses issue #123" -->
  +
  +##### Context
  +
  +<!-- Are there any parts that you've intentionally left out-of-scope for a later PR to handle? -->
  +
  +<!-- Were there any alternative approaches you considered? What tradeoffs did you consider? -->
  #### Pull request checklist
  <!-- If a checklist item is not applicable to this change, write "n/a" in the checkbox -->
  