docs: mention breaking changes in PR template (#413)

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,13 +1,14 @@
 Please fill in the fields below to submit a pull request.  The more information that is provided, the better.
 
 Fixes #<Issue>
+
 Release Notes: <!-- What comments/remarks should we include in the release notes for this change? -->
 
 **Types of changes**:
 <!--- What types of changes does your code introduce? Put an `x` in all the boxes that apply: -->
 - [ ] Bug fix (non-breaking change which fixes an issue)
 - [ ] New feature (non-breaking change which adds functionality)
-- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected). **Please ensure that your PR title** is a [Conventional Commit](https://www.conventionalcommits.org/en/v1.0.0/) breaking change (with a `!`, as in `feat!: change foo`). 
 
 **Description of the changes being introduced by the pull request**: