Add description to release

Author: stefanv

.github/workflows/release.yaml

@@ -65,6 +65,16 @@ jobs:
       - name: Release
         uses: softprops/action-gh-release@v2
         with:
+          body: |
+            This is the ${{ env.ISODATE }} snapshot of developer
+            statistics for [Scientific Python](https://scientific-python.org)
+            [core projects](https://scientific-python.org/specs/core-projects/).
+
+            You can generate a report from this data using
+            [devstats](https://github.com/scientific-python/devstats).
+
+            \`${{ env.FILENAME }}\` contains the queries used for this
+            release.
           tag_name: ${{ env.ISODATE }}
           files: |
             *.xz