Backport #39631 by @stackedbyaradhya
Release webhook notifications never mention attached files, although the
payload carries them.
The summary shared by all webhook providers now appends an asset count
like `(assets: 2)` for created and updated releases.
Closes https://github.com/go-gitea/gitea/issues/39630
Co-authored-by: Aradhya Jain <aradhyaj736@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>