chore: Update PR template for SIP-59 DB migrations process (#13855)

diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
index 4d6b88e..2468293 100644
--- a/.github/PULL_REQUEST_TEMPLATE.md
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -12,7 +12,9 @@
 <!--- HINT: Include "Fixes #nnn" if you are fixing an existing issue -->
 - [ ] Has associated issue:
 - [ ] Changes UI
-- [ ] Requires DB Migration.
-- [ ] Confirm DB Migration upgrade and downgrade tested.
+- [ ] Includes DB Migration (follow approval process in [SIP-59](https://github.com/apache/superset/issues/13351))
+  - [ ] Migration is atomic, supports rollback & is backwards-compatible
+  - [ ] Confirm DB migration upgrade and downgrade tested
+  - [ ] Runtime estimates and downtime expectations provided
 - [ ] Introduces new feature or API
 - [ ] Removes existing feature or API