The page at logcheck dot org contains questionable links and it is unclear
whether it is controlled by the logcheck project at all. Fix by using the
homepage debian points to instead.
Fixes https://github.com/NixOS/nixpkgs/issues/24952
* Remove package name
* Start with upper case letter
* Remove trailing period
Also reword some descriptions and move some long descriptions to
longDescription.
I'm not touching generated packages.