Update new service intro section in PR template (#891)

Author: YuryHrytsuk

.github/PULL_REQUEST_TEMPLATE.md

@@ -17,7 +17,7 @@
 - [ ] Service has resource limits and reservations
 - [ ] Service has placement constraints or is global
 - [ ] Service is restartable
-  - [ ] The restart is zero-downtime
+- [ ] Service restart is zero-downtime
 - [ ] Service is not bound to one specific node (e.g. via files or volumes)
-- [ ] Relevant OPS E2E Test for this stack were added
--->
+- [ ] Relevant OPS E2E Test are added
+- [ ] Service's Public URL is included in maintenance mode -->