Attempt to extract the changelog entry for the tag

Author: james-allan

.github/workflows/nightly-build.yml

@@ -39,13 +39,35 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
+      # Extract the latest changelog section
+      # Pulls everything after the first version header like "= 8.1.0 - ... =" until the next "=" section header or end of file
+      - name: Extract latest changelog section
+        id: changelog
+        run: |
+          version_line_found=0
+          echo "CHANGELOG<<EOF" >> $GITHUB_OUTPUT
+          while IFS= read -r line; do
+            if [[ $line == =\ *\ = ]]; then
+              if [[ $version_line_found -eq 1 ]]; then
+                break
+              else
+                version_line_found=1
+                echo "$line" >> $GITHUB_OUTPUT
+              fi
+            elif [[ $version_line_found -eq 1 ]]; then
+              echo "$line" >> $GITHUB_OUTPUT
+            fi
+          done < changelog.txt
+          echo "EOF" >> $GITHUB_OUTPUT
+
       - name: Create or Update GitHub Release
         uses: softprops/action-gh-release@v2
         with:
           tag_name: Nightly
           release_name: "Nightly Build"
           prerelease: true
           draft: false
+          body: ${{ steps.changelog.outputs.CHANGELOG }}
           files: woocommerce-subscriptions-core.zip
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}