Add hash files (md5/sha)

[drdanz]

It would be useful to have a file containing the hash for the zip files.
In this way, inside the continuous integration, it would be possible to cache the files, and download the new ones only if the hash does not match.

[traversaro]

Were you thinking a hash file added to the github releases pages or something else?

[drdanz]

Yes, just adding something like

md5sum vcpkg-robotology.zip > vcpkg-robotology.zip.md5

and publishing the generated file should be enough...