chore: update PR template COMPASS-10019 (#7535)

Author: johnjackweir

.github/PULL_REQUEST_TEMPLATE.md

@@ -18,11 +18,12 @@
 - [ ] New tests and/or benchmarks are included
 - [ ] Documentation is changed or added
 - [ ] If this change updates the UI, screenshots/videos are added and a design review is requested
+- [ ] If this change could impact the load on the MongoDB cluster, please describe the expected and worst case impact
 - [ ] I have signed the MongoDB Contributor License Agreement (https://www.mongodb.com/legal/contributor-agreement)
 
 ## Motivation and Context
 <!--- Why is this change required? What problem does it solve? -->
-<!--- If it's updating a dependancy, link to the Pull Request that originally introduced the fix -->
+<!--- If it's updating a dependency, link to the Pull Request that originally introduced the fix -->
 - [ ] Bugfix
 - [ ] New feature
 - [ ] Dependency update