Add PR Template Section for Backward Compatibility Breaking Changes (#1699)

This PR updates the PR template to include a section where developers can include changes that break backward compatibility.

Co-authored-by: Neal Sun <nesun@nesun-mn1.linkedin.biz>
diff --git a/.github/pull_request_template.md b/.github/pull_request_template.md
index f2c3025..1720331 100644
--- a/.github/pull_request_template.md
+++ b/.github/pull_request_template.md
@@ -21,6 +21,12 @@
 
 (If CI test fails due to known issue, please specify the issue and test PR locally. Then copy & paste the result of "mvn test" to here.)
 
+### Changes that Break Backward Compatibility (Optional)
+
+- My PR contains changes that break backward compatibility or previous assumptions for certain methods or API. They include:
+
+(Consider including all behavior changes for public methods or API. Also include these changes in merge description so that other developers are aware of these changes. This allows them to make relevant code changes in feature branches accounting for the new method/API behavior.)
+
 ### Documentation (Optional)
 
 - In case of new functionality, my PR adds documentation in the following wiki page: