Chocolatey package available - add documentation

[nzbart]

Although this project appears to no longer be maintained, it's still useful to a lot of people. I've added a Chocolatey package for Windows users:

• https://chocolatey.org/packages/xsv

It would be more obvious if this was added to the documentation, but this issue will still be discoverable by anyone interested even if it's not documented in the readme.