delete secrets artifact, update readme

.github/workflows/generator-windows-x86.yml

@@ -506,3 +506,14 @@ jobs:
           method: 'POST'
           customHeaders: '{"Content-Type": "application/json"}'
           data: '{"uuid": "${{ env.uuid }}", "status": "Generation cancelled, try again"}'
+
+  cleanup:
+    needs: [build-for-windows-sciter]
+    runs-on: ubuntu-latest
+    continue-on-error: true
+    if: always()
+    steps:
+      - name: Delete secrets artifact
+        uses: geekyeggo/delete-artifact@v5
+        with:
+          name: encrypted-secrets-zip