Make bold emphasize important non-link word

.github/PULL_REQUEST_TEMPLATE.md

@@ -12,9 +12,9 @@
 ## Checklist:
 <!-- This checklist must be complete before merging the pull request. -->
 <!-- If you are unsure about any of these items, do not hesitate to ask! -->
-- [ ] I am familiar with the [**Contributing Guidelines**](https://github.com/glotzerlab/signac/blob/master/CONTRIBUTING.md).
-- [ ] I agree with the terms of the [**Contributor Agreement**](https://github.com/glotzerlab/signac/blob/master/ContributorAgreement.md).
+- [ ] I am familiar with the [Contributing Guidelines](https://github.com/glotzerlab/signac/blob/master/CONTRIBUTING.md).
+- [ ] I agree with the terms of the [Contributor Agreement](https://github.com/glotzerlab/signac/blob/master/ContributorAgreement.md).
 - [ ] My name is on the [list of contributors](https://github.com/glotzerlab/signac/blob/master/contributors.yaml).
-- [ ] The changes introduced by this pull request are covered by existing or newly introduced tests.
+- [ ] The changes introduced by this pull request are covered by existing or newly introduced **tests**.
 - [ ] The [package documentation](../tree/master/doc) and [framework documentation](https://docs.signac.io/) in [signac-docs](https://github.com/glotzerlab/signac-docs) are up to date with these changes.
 - [ ] I have updated the [changelog](https://github.com/glotzerlab/signac/blob/master/changelog.txt) and added any related issue and pull request numbers for future reference.