Link to migration guide tempalte from pull request template (#58027)

diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
index b06e5ac..ed84a1b 100644
--- a/.github/PULL_REQUEST_TEMPLATE.md
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -34,7 +34,7 @@
 - [ ] Yes, this is a breaking change. *If not, delete the remainder of this section.*
    - [ ] I wrote a design doc: https://flutter.dev/go/template *Replace this with a link to your design doc's short link*
    - [ ] I got input from the developer relations team, specifically from: *Replace with the names of who gave advice*
-   - [ ] I wrote a migration guide: *Replace with a link to your migration guide*
+   - [ ] I wrote a migration guide: https://flutter.dev/go/breaking-changes-template *Replace this with a link to a pull request that adds the migration guide to https://flutter.dev/docs/release/breaking-changes*
 
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