Those freedoms are: (0) the freedom to run the software as desired and for any purpose, (1) the freedom to study or change the software, (2) the freedom to redistribute copies of the software, and (3) the freedom to distribute modified copies of the software. The numbering of these four freedoms begins with zero because “Freedom 0” was added to the list after the other three, but it is considered more foundational than the others.
Usually I hate this, I'm using man for a reason, but sometimes I'm scrolling through a novel-length man page thinking that maybe most of this information needs to be anywhere else.
And sometimes the URL is broken. The man page for powertop is like that. Says "for full documentation, go to this link", the link doesn't work any more, and I asked the developer about it and he can't even remember what was at the URL.