Include BIND documentation in Windows zips

As generated documentation files are no longer stored in the BIND Git repository, put a copy of the PDF version of the BIND ARM generated by the "docs" GitLab CI job into the Windows zips to make it easily available to the end users on that platform.

Make sure Windows zips also contain certain documentation files included in source tarballs to make the contents of each release more consistent across different platforms.

Closes #1919 (closed)