message: Suggest SR testing of UI changes in PR template
  Adds a line to our PR checklist for doing screen reader testing of UI changes
diff: - [ ] Added relevant unit test for your changes. (`npm run test`)
  - [ ] Verified code coverage for the changes made. Check coverage report at: `<rootDir>/test-results/unit/coverage`
  - [ ] Ran precheckin (`npm run precheckin`)
  -- [ ] Added screenshots/GIFs for UI changes.
  +- [ ] (UI changes only) Added screenshots/GIFs to description above
  +- [ ] (UI changes only) Verified usability with NVDA/JAWS
  