Add a pull request template to the master branch.

.github/pull_request_template.md

@@ -0,0 +1,18 @@
+## Pull Request Testing ##
+
+- [ ] Describe testing already performed for these changes:</br>
+
+- [ ] Recommend testing for the reviewer to perform, including the location of input datasets:</br>
+
+- [ ] Will this PR result in changes to the test suite? **[Yes or No]**</br>
+If **yes**, describe the new output and/or changes to the existing output:</br>
+
+- [ ] After merging, should the reviewer **DELETE** the feature branch from GitHub? **[Yes or No]**</br>
+
+## Pull Request Checklist ##
+See the [METplus Workflow](https://dtcenter.github.io/METplus/Contributors_Guide/github_workflow.html) for details.
+- [ ] Complete the PR definition above.
+- [ ] Ensure the PR title matches the feature or bugfix branch name.
+- [ ] Define the PR metadata, as permissions allow.
+Select: **Reviewer(s)**, **Project(s)**, and **Milestone**
+- [ ] After submitting the PR, select **Linked Issues** with the original issue number.