scoop manifest for windows users

- Firstly thankyou to the developer(s)
- Consider submitting a scoop "app manfest file" to make it even easier for windows users to install xxhsum
- scoop [1] is a package manager for windows that automates the version checking, downloading, installing in a portable way for unprivileged users and doing the the install/update.
- It could go into the scoop extras bucket perhaps.
- See [2][3] for info and examples on manifest files

**Ref**:
- [1] https://scoop.sh/
- [2] https://github.com/ScoopInstaller/Scoop/wiki/App-Manifests
- [3] https://github.com/ScoopInstaller/Extras/tree/master/bucket

Start with the Scoop App-Manifests guide and the linked Extras bucket examples. Work out the manifest details needed to install xxhsum for Windows, then submit it to the appropriate Scoop bucket and verify that the manifest supports installation and updates.

Written by the indexing model from the issue text.