add step to check the PR URL is included in the CHANGELOG.md file

.github/workflows/changelog.yml

@@ -4,6 +4,10 @@ on:
   pull_request:
     types: [opened, synchronize, reopened, ready_for_review, labeled, unlabeled]
 
+env:
+  PR_NUMBER: ${{ github.event.number }}
+  PR_URL: https://github.com/Layr-Labs/eigensdk-rs/pull/$PR_NUMBER
+
 jobs:
   # Enforces the update of a changelog file on every pull request 
   # We only want this for user-visible changes, so we add a few labels
@@ -14,3 +18,7 @@ jobs:
     - uses: dangoslen/changelog-enforcer@v3
       with:
         skipLabels: pipelines,tests,documentation
+
+    - name: Enforce PR URL in CHANGELOG.md
+    - run: grep $PR_URL CHANGELOG.md
+