## Type of Change
- [x] Process update
## Description
Remove description field in PR template
## Motivation and Context
I think having separate `Description` and `Motivation and Context`
sections have been redundant in recent usage of the PR template. This PR
removes the `Description` section. Ideally the PR title should cover the
same content previously in the `Description` section.
Signed-off-by: Kathryn Baldauf <k_baldauf@apple.com>