add bug Checklist, update PR documentation (#13364)

Author: ousmaneo

.github/ISSUE_TEMPLATE/bug_report.md

@@ -42,3 +42,7 @@ assignees: ''
 * MongoDB Version:
 * Operating System:
 * Browser version:
+
+## Checklist
+[] This issue fix need to be backported.
+[] Does this issue have **security** implications? 

.github/PULL_REQUEST_TEMPLATE.md

@@ -26,7 +26,7 @@
 <!--- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
 - [ ] My code follows the code style of this project.
 - [ ] My change requires a change to the documentation.
-- [ ] I have updated the documentation accordingly.
+- [ ] I have requested a documentation update.
 - [ ] I have read the **CONTRIBUTING** document.
 - [ ] I have added tests to cover my changes.