Command for downloading and extracting of EPUBCheck does not work when used verbatim

[martinpub]

Hi!

I noticed that the current installation instructions for macOS and Linux suggest the following command to download and extract the latest version of EPUBCheck:

curl -SL https://github.com/w3c/epubcheck/releases/download/v5.3.0/epubcheck-5.3.0.zip | tar -xf -

However, piping to tar requires a tar package (at least with GNU tar), and the URL provides a zip package.

It would be good if the instructions were updated to correct this. It seems unzip cannot read from stdin, so perhaps the line needs to be split up.

Thanks!