htmlpurifier.org website and download methods

Thank you for the excellent HTML Purifier. We need to update our installation as we migrate an internal website from an old server/OS to a new one running PHP 7, and so we need to update our package dependencies as well.

Just a few small issues about the download instructions at: http://htmlpurifier.org/download
…in case these may also confuse other people.

We had previously used the PEAR install, but the HTML Purifier PEAR repo no longer seems to work properly? We get offered HTMLPurifier-4.11.0.tgz, but it seems to be corrupt? (I'm aware that PEAR seems to be slowly being quietly deprecated, so we should probably move away from this in any case, but just noting the issue.)

The download page states that repo.or.cz should be regarded as the main repo, but the latest version that it seems to have is v4.10.0.

It looks as though GitHub is where HTML Purifier activity is now, but it is slightly confusing that wording of the official website rather suggests that this is not the case.

Start with the download page at http://htmlpurifier.org/download and compare its PEAR, repo.or.cz, and GitHub instructions with the current project locations and the reported HTMLPurifier-4.11.0.tgz problem. Update the wording and download guidance so the active source and working installation method are clear; the page should no longer direct users toward outdated or broken options.