Add PR template to OGE

[grgmiller]

Add a PR template to help guide PRs moving forward.

Example that should be improved on:

Summary

A summary of this PR in a couple sentences

Where to look

What files were changed?

Update details

Document in more depth the changes being made

Screenshots

A couple screenshots of the changes/data if relevant.

Testing / Validation

What testing was done, this can be unit tests, manual testing, etc.

Linear ticket

(required for internal Singularity tracking)

Concerns

Anything you'd like to point out that the reviewers should pay special attention to

Next steps / Not addressed here

if relevant, add a couple bullet points on follow-on work to this PR or issues that are not addressed here.

Checklist

• Update the documentation to reflect changes made in this PR