Update BenchmarkPR.yml

Author: ErikQQY

.github/workflows/BenchmarkPR.yml

@@ -52,8 +52,8 @@ jobs:
         run: |
           benchpkgtable ${{ steps.extract-package-name.outputs.package_name }} --rev="${{github.event.repository.default_branch}},${{github.event.pull_request.head.sha}}" --input-dir=results/ --ratio > table.md
           echo '### Benchmark Results' > body.md
-          echo '<details>' > body.md
-          echo '<summary>Click to check benchmark results</summary>' > body.md
+          echo '<details>' >> body.md
+          echo '<summary>Click to check benchmark results</summary>' >> body.md
           echo '' >> body.md
           echo '' >> body.md
           cat table.md >> body.md