There is no location where Szczepan’s fingerprint for his public key can be verified. At the moment it has the same security level as a checksum, but the checksums are available already. So it is not really reasonable to provide the signature file.
Indeed, it is missed somehow. I will ask @nitroalex to add it to main download site’s description. In the meantime please see my Github profile, where I have added it into my Bio: https://github.com/szszszsz .
I will add it too to the Release page description.
Edit: included into my forum’s profile
did add it to the download page, thanks for your feedback!